# Patent

## Title
Request routing management based on network components

## Abstract

Systems and methods for managing requesting routing functionality associated with resource requests for one or more resources associated with a content provider are provided. A content delivery network (“CDN”) service provider, on behalf of a content provider, can process domain name service (“DNS”) requests for resources by computing devices and resolve the DNS requests by the identification of a network address of a computing device that will provide the requested resources. Based on the processing of DNS queries initiated by a client computing device, the CDN service provider can measure CDN service provider latencies associated with the generation of DNS requests by network components associated with the client computing devices. Examples of the network components can include DNS resolvers associated with the client computing device.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 12/892,880, now U.S. Pat. No. 8,577,992, entitled REQUEST ROUTING MANAGEMENT BASED ON NETWORK COMPONENTS and filed on Sep. 28, 2010, the disclosure of which is incorporated herein by reference.


BACKGROUND
Generally described, computing devices and communication networks can be utilized to exchange information. In a common application, a computing device can request content from another computing device via the communication network. For example, a user at a personal computing device can utilize a software browser application to request a Web page from a server computing device via the Internet. In such embodiments, the user computing device can be referred to as a client computing device and the server computing device can be referred to as a content provider.
Content providers are generally motivated to provide requested content to client computing devices often with consideration of efficient transmission of the requested content to the client computing device and/or consideration of a cost associated with the transmission of the content. For larger scale implementations, a content provider may receive content requests from a high volume of client computing devices which can place a strain on the content provider's computing resources. Additionally, the content requested by the client computing devices may have a number of components, which can further place additional strain on the content provider's computing resources.
With reference to an illustrative example, a requested Web page, or original content, may be associated with a number of additional resources, such as images or videos, which are to be displayed with the Web page. In one specific embodiment, the additional resources of the Web page are identified by a number of embedded resource identifiers, such as uniform resource locators (“URLs”). In turn, software on the client computing devices typically processes embedded resource identifiers to generate requests for the content. Often, the resource identifiers associated with the embedded resources reference a computing device associated with the content provider such that the client computing device would transmit the request for the additional resources to the referenced content provider computing device. Accordingly, in order to satisfy a content request, the content provider would provide client computing devices data associated with the Web page as well as the data associated with the embedded resources.
Some content providers attempt to facilitate the delivery of requested content, such as Web pages and/or resources identified in Web pages, through the utilization of a content delivery network (“CDN”) service provider. A CDN service provider typically maintains a number of computing devices in a communication network that can maintain content from various content providers. In turn, content providers can instruct, or otherwise suggest to, client computing devices to request some, or all, of the content provider's content from the CDN service provider's computing devices.
As with content providers, CDN service providers are also generally motivated to provide requested content to client computing devices often with consideration of efficient transmission of the requested content to the client computing device and/or consideration of a cost associated with the transmission of the content. Accordingly, CDN service providers often consider factors such as latency of delivery of requested content in order to meet service level agreements or to generally improve the quality of delivery service. Additionally, in embodiments in which computing devices utilize an Internet service provider (“ISP”) to provide connectivity, the CDN service provider can consider additional factors associated with the interaction between the CDN service provider, client computing and ISP devices, such as a DNS resolver component.



BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a block diagram illustrative of content delivery environment including a number of client computing devices, a content provider, and a content delivery network service provider;
FIG. 2 is a block diagram of the content delivery environment of FIG. 1 illustrating the registration of a content provider with a CDN service provider;
FIG. 3 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation of resource requests by a client computing device;
FIG. 4 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation of DNS queries by a client computing device corresponding to embedded resources by a client computing device;
FIG. 5 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation of DNS queries by a client computing device corresponding to alternative identifiers by a client computing device;
FIG. 6 is a block diagram of the content delivery environment of FIG. 1 illustrating the transmission of DNS queries by a client computing device in accordance with a network routing scheme by a client computing device;
FIG. 7 is a block diagram of the content delivery environment of FIG. 1 illustrating the transmission of DNS queries by a client computing device in accordance with an alternative network routing scheme by a client computing device;
FIG. 8 is a block diagram of the content delivery environment of FIG. 1 illustrating the transmission of DNS queries by a client computing device in accordance with an alternative network routing scheme by a client computing device; and
FIG. 9 is a flow diagram illustrative of a request routing processing routine implemented by a service provider.



DETAILED DESCRIPTION
Generally described, the present disclosure is directed to managing request routing functionality associated with resource requests for one or more resources associated with a content provider. Specifically, aspects of the disclosure will be described with regard to the management and processing of request routing functionality by a service provider, such as a content delivery network (“CDN”) service provider, on behalf of a content provider. Illustratively, the request routing functionality can correspond to the processing of domain name service (“DNS”) requests for resources by computing devices and the resolution of the DNS requests by the identification of a network address of a computing device that will provide the requested resources. Based on the processing of DNS queries initiated by a client computing device, the CDN service provider can measure CDN service provider performance measurement information associated with the generation and processing of DNS requests by network components associated with the client computing devices. Examples of the network components can include DNS resolvers associated with the client computing device. Additionally, examples of performance measurement information can include the measurement of latencies associated with transmitting and processing the DNS queries, data packet loss associated with the transmittal of the DNS queries, data throughput associated with the transmittal of the DNS queries, available bandwidth associated with a communication channel and the like.
Although various aspects of the disclosure will be described with regard to illustrative examples and embodiments, one skilled in the art will appreciate that the disclosed embodiments and examples should not be construed as limiting. For example, the present disclosure may be described with regard to request routing services provided by a service provider, such as a CDN service provider, that may provide additional services and functionality including network-based storage services, caching services, application hosting, or other services. However, one skilled in the relevant art will appreciate that a service provider need not provide all, or any, of the additional services or functionality that may be associated with some service providers, such as a CDN service provider.
FIG. 1 is a block diagram illustrative of content delivery environment 100 for the managing registration of a content provider with a service provider, such as a CDN service provider, and subsequent processing of at least a portion of content requests on behalf of the content provider. As illustrated in FIG. 1, the content delivery environment 100 includes a number of client computing devices 102 (generally referred to as clients) for requesting content from a content provider 104, a network storage provider, and/or a CDN service provider 106. In an illustrative embodiment, the client computing devices 102 can correspond to a wide variety of computing devices including personal computing devices, laptop computing devices, hand-held computing devices, terminal computing devices, mobile devices, wireless devices, various electronic devices and appliances and the like. In an illustrative embodiment, the client computing devices 102 include necessary hardware and software components for establishing communications over a communication network 112, such as a wide area network or local area network. For example, the client computing devices 102 may be equipped with networking equipment and browser software applications that facilitate communications via the Internet or an intranet.
Illustratively, at least some of the client computing devices 102 utilize a DNS resolver component 108, such as a DNS name server, that receives DNS queries from a client computing device 102 and then generates the DNS queries attributed to the client computing device, or on behalf of the client computing device. In one embodiment, the DNS resolver component 108 may be a local DNS component provided by an enterprise network to which the client computing device 102 belongs. In another embodiment, the local DNS resolver component 108 may be provided by an Internet Service Provider (“ISP”) that provides the communication network connection to the client computing device 102. In embodiments in which the client computing devices 102 utilize a DNS resolver component 108, one skilled in the relevant art will appreciate that the DNS queries generated on behalf of the client computing devices would be associated with the IP address of the DNS resolver component 108 in accordance with traditional networking protocols. In further embodiments, a client computing device 102 may be associated with multiple DNS resolver components 108, such as a multi-tiered hierarchy of DNS resolver components. For example, a client computing device 102 may be associated with a first DNS resolver component 108 provided by an enterprise network, which in turn is in communication with one or more DNS resolver components provided by an ISP. In other examples, a single network provider may make multiple DNS resolver components 108 available or responsive to the client computing device 102 DNS queries.
The content delivery environment 100 can also include a content provider 104 in communication with the one or more client computing devices 102 via the communication network 110. The content provider 104 illustrated in FIG. 1 corresponds to a logical association of one or more computing devices associated with a content provider. Specifically, the content provider 104 can include a web server component 112 corresponding to one or more server computing devices for obtaining and processing requests for content (such as Web pages) from the client computing devices 102. The content provider 104 can further include an origin server component 114 and associated storage component 116 corresponding to one or more computing devices for obtaining and processing requests for network resources. One skilled in the relevant art will appreciate that the content provider 104 can be associated with various additional computing resources, such additional computing devices for administration of content and resources and the like. Additionally, although the origin server component 114 and associated storage component 116 are logically associated with the content provider 104, the origin server component 114 and associated storage components 116 may be geographically distributed throughout the communication network 112 in a manner to best serve various demographics of client computing devices 102.
Although not illustrated in FIG. 1, the content provider 104 can be associated with a number of additional or supplement components to facilitate interaction with client computing devices 102 or service providers. For example, a content provider 104 may maintain one or more DNS name server components that are operative to receive DNS queries related to registered domain names associated with the content provider 104. The one or more DNS name servers can be authoritative to resolve client computing device DNS queries corresponding to the registered domain names of the content provider 104. The content provider 104 can also maintain additional storage components, such as proxy servers, or utilize network storage service providers to maintain at least a portion of the content/resources provided to the client computing devices 102.
With continued reference to FIG. 1, the content delivery environment 100 can further include a service provider, generally referred to as the CDN service provider 106, in communication with the one or more client computing devices 102 and the content provider 104 via the communication network 110. The CDN service provider 106 illustrated in FIG. 1 corresponds to a logical association of one or more computing devices associated with a service provider. Specifically, the CDN service provider 106 can include a number of Point of Presence (“POP”) locations 118, 124 that correspond to nodes on the communication network 110. Each POP 118, 124 includes a DNS component 120, 126 made up of a number of DNS server computing devices for resolving DNS queries from the client computers 102. Each POP 118, 124 also optionally includes a resource cache component 122, 128 made up of a number of cache server computing devices for storing resources from content providers or network storage providers and transmitting various requested resources to various client computers 102. The DNS components 120, 126 and the resource cache components 122, 128 may further include additional software and/or hardware components that facilitate communications, including, but not limited to, load balancing or load sharing software/hardware components.
Still further, the CDN service provider 106 can include additional data stores for managing request routing information. Specifically, in an illustrative embodiment, the CDN service provider 106 can include a DNS resolver log data store 130 for maintaining information regarding DNS queries provided by the DNS resolvers 108 on behalf of client computing devices 102. As previously described, examples of performance measurement information can include latency information, data packet loss information, data throughput information, available bandwidth associated with a communication channel, and the like. Additionally, the DNS resolver log data can further include performance measurement information or other information associated with the transmittal or processing of DNS queries. Although the DNS resolver log data store 130 is illustrated as a single, centrally located data store, one skilled in the relevant art will appreciate that the DNS resolver log data store 130 may be distributed among several data stores or be maintained, at least in part, among the POPs 118, 124.
In an illustrative embodiment, the DNS component 120, 126 and resource cache component 122, 128 are considered to be logically grouped, regardless of whether the components, or portions of the components, are physically separate. Additionally, although the POPs 118, 124 are illustrated in FIG. 1 as logically associated with the CDN service provider 106, the POPs will be geographically distributed throughout the communication network 110 in a manner to best serve various demographics of client computing devices 102. Additionally, one skilled in the relevant art will appreciate that the CDN service provider 106 can be associated with various additional computing resources, such as additional computing devices for administration of content and resources, and the like. Even further, the components of the CDN service provider 106 can be managed by the same or different entities. One skilled in the relevant art will also appreciate that the components and configurations provided in FIG. 1 are illustrative in nature. Accordingly, additional or alternative components and/or configurations, especially regarding the additional components, systems and subsystems for facilitating communications may be utilized.
With reference now to FIGS. 2-8, the interaction between various components of the content delivery environment 100 of FIG. 1 will be illustrated. For purposes of the example, however, the illustration has been simplified such that many of the components utilized to facilitate communications are not shown. One skilled in the relevant art will appreciate that such components can be utilized and that additional interactions would accordingly occur without departing from the spirit and scope of the present disclosure.
With reference to FIG. 2, an illustrative interaction for the optional registration of a content provider 104 with the CDN service provider 106 for hosting content on behalf of the content provider 104 will be described. As illustrated in FIG. 2, the CDN service provider content registration process begins with registration of the content provider 104 with the CDN service provider 106. In an illustrative embodiment, the content provider 104 utilizes a registration application program interface (“API”) to register with the CDN service provider 106 such that the CDN service provider 106 can provide content on behalf of the content provider 104, or at least perform the processes described herein. Illustratively, the registration API can include the identification of the origin server 114 of the content provider 104 that may provide requested resources to the CDN service provider 106. In addition or alternatively, the registration API can include the content to be stored by the CDN service provider 106 on behalf of the content provider 104. Additionally, the content provider 104 can specify one or more network storage providers (not illustrated) that may act as an origin server for the content provider 104.
The CDN service provider 106 returns the embedded resource identifiers to the content provider 104 along with any additional information. In turn, the content provider 104 can then store the embedded resource identifiers for embedding in requested content or otherwise embed (or associate) the embedded resource identifiers with requested content (such as Web page markup language), which are described in greater detail below. In an illustrative embodiment, the embedded resource identifiers can be applicable to multiple content providers 104. Alternatively, the embedded resource identifiers can be unique to each particular content provider 104. Still further, the CDN service provider 106 may provide additional logic to the content providers 104 that controls the circumstances and/or methodologies for embedding the embedded resource identifiers into content. For example, the embedded resource identifiers can include instructions (or executable code) that defines the type of content (e.g., specific Web pages) for which the embedded resource identifiers will apply.
With reference now to FIG. 3, after completion of the registration and embedding processes illustrated in FIG. 2, a client computing device 102 generates a content request that is received and processed by the content provider 104, such as through the Web server 112. In accordance with an illustrative embodiment, the request for content can be in accordance with common network protocols, such as the hypertext transfer protocol (“HTTP”). Upon receipt of the content request, the content provider identifies the appropriate responsive content. In an illustrative embodiment, the requested content can correspond to a Web page that is displayed on the client computing device 102 via the processing of information, such as hypertext markup language (“HTML”), extensible markup language (“XML”), and the like. The requested content can also include a number of embedded resource identifiers that correspond to resource objects that should be obtained by the client computing device 102 as part of the processing of the requested content. The embedded resources can correspond to multi-media content, such as images, videos, text, etc. that will be processed by the client computing devices 102 and rendered on an output device. Although not illustrated in FIG. 3, the client computing device 102 would first issue a DNS query for the content provided by the content provider 104, which if properly resolved, would include the identification of the above mentioned IP address associated with the content provider. One skilled in the relevant art will appreciate that the resolution of the DNS query may involve multiple DNS queries to either the content provider 104 or other service provider.
Generally, the identification of the embedded resources provided by the content provider 104 will be in the form of resource identifiers that can be processed by the client computing device 102, such as through a browser software application. In an illustrative embodiment, the resource identifiers can be in the form of a uniform resource locator (“URL”). For purposes of an illustrative example, the URL can identify a domain of the CDN service provider 106 (e.g., CDNserviceprovider.com), a name of a resource to be requested (e.g., “resource.xxx”) and a path where the resource will be found (e.g., “path”). Additionally, in an illustrative embodiment, the URL can also include one or more labels that include additional information utilized by the CDN service provider 106 in the request routing process (e.g., “additional_information”). Examples of the additional information can include client computing device identifiers, user account identifiers, geographic identification information, POP identifiers, DNS resolver performance measurement identification information, and the like. In this illustrative example, the URLs of the embedded resource have the form of:

    
    
        http://additional_information.CDNserviceprovider.com/path/resource.xxx
    
    


With reference now to FIG. 4, upon receipt of the requested content, including the embedded resource identifiers provided by the CDN service provider 106, the client computing device 102 would first transmit a DNS query through its DNS resolver 108 to request an IP address of a computing device corresponding to the unique identifier provided by the CDN service provider 106. In accordance with traditional request routing principles, the DNS query would be received by the DNS resolver 108 and then transmitted on behalf of the requesting client computing device 102.
By way of example, in accordance with traditional DNS request routing principles, a DNS query for the URL http://additional_information.CDNserviceprovider.com/path/resource.xxx would first include the identification of a DNS server authoritative to the “.” and the “com” portions of the URL to the DNS resolver 108. The issuance of DNS queries corresponding to the “.” and the “com” portions of a URL are well known and have not been illustrated. After partially resolving the modified URL according to the “.” and “com” portions of the URL, the DNS resolver 108 then issues another DNS query for the resource URL that results in the identification of the DNS server corresponding to the “.CDNserviceprovider” portion of the URL, as illustrated in FIG. 4, illustrated as the DNS server component 120 of POP 118.
The receiving DNS server component 120 obtains the DNS query from the DNS resolver component 108 and processes the DNS query. In an illustrative embodiment, the DNS server component 120 determines that the processing of the DNS query should be, at least in part, used to measure performance of the DNS resolver 108 or other network component. In one embodiment, the DNS query may not correspond to an actual resource that will be delivered to the client computing device 102. In this embodiment, the resolution of the DNS query may result in no response from a DNS server. In another embodiment, the resolution of the DNS query may result in the generation of additional actions/responses from the DNS server for purposes of performance measurement.
Alternatively, the DNS query may correspond to an actual resource provided by the CDN service provider 106 on behalf of the content provider 104. Illustratively, the “additional_information” portion of the URL may include information that will be utilized to determine whether the CDN service provider 106 should utilize the DNS query for performance measurement or will be utilized in the determination of the performance measurement. For example, a client computing device may execute a script prior to the generation of the DNS query that modifies the URL to include various identifiers or timing information to the URL.
To facilitate the performance measurement, the receiving POP, POP 118, can obtain information from the DNS query or collect additional information. The collected information can be maintained in the DNS resolver log data store 130. One skilled in the relevant art will appreciate, that typically, a receiving DNS server can resolve DNS queries by identifying an IP address of a cache server component, such resource cache component 122, that will process the request for the requested resource. The selected resource cache component can process the request by either providing the requested resource if it is available or attempting to obtain the requested resource from another source, such as a peer cache server computing device or the origin server 114 of the content provider 104. However, in this illustrative embodiment, as an alternative to selecting a cache server component, the CDN service provider 106 can maintain sets of various alternative resource identifiers that can be utilized for more refined request routing purposes. Additionally, in this embodiment, the alternative resource identifiers can be utilized to measure the performance of the DNS resolver component 108 (or other network components). Specifically, the alternative resource identifiers can be provided by the CDN service provider 106 to the client computing device 102 such that a subsequent DNS query on the alternative resource identifier will resolve to a different DNS server component within the CDN service provider's network.
In an illustrative embodiment, the alternative resource identifiers are in the form of one or more canonical name (“CNAME”) records. In one embodiment, each CNAME record identifies a domain of the CDN service provider 106 (e.g., “cdnprovider.com” or “cdnprovider-1.com”). As will be explained in greater detail below, the domain in the CNAME does not need to be the same domain found in original URL or in a previous CNAME record. Additionally, each CNAME record includes additional information (e.g., “additional information”), such as request routing information, performance measurement information, and the like. An illustrative CNAME record can have the form of:

    
    
        CNAME additional_information.cdnprovider.com
    
    


In an illustrative embodiment, the CNAME records are generated and provided by the DNS servers to direct DNS queries to a different DNS server of the CDN service provider 106. In one embodiment, the subsequent DNS queries (corresponding to the CNAME) will be directed, or otherwise be received by, a different DNS server of the CDN service provider 106. As will be explained in greater detail below, the CNAME can include additional request routing information that causes the DNS query to be received by a different POP or otherwise cause the subsequent DNS query to be forwarded to a DNS server at a different POP. In other embodiments, the subsequent DNS queries will be directed toward the same DNS server that received the previous DNS query.
In some embodiments, the selection of different DNS servers to receive one or more subsequent DNS queries may be based on a determined appropriateness of other DNS servers to process DNS queries from a particular client computing device 102 or set of client computing devices. As used in accordance with the present disclosure, appropriateness can be defined in any manner by the CDN service provider 106 for a variety of purposes. In one example, the CDN service provider 106 can attempt to direct DNS queries to DNS servers, such as in the returned CNAME, according to geographic criteria. The geographic criteria can correspond to geographic-based regional service plans contracted between the CDN service-provider 106 and the content provider 104 in which various CDN service provider 106 POPs are grouped into geographic regions. Accordingly, a client computing device 102 DNS query received in a region not corresponding to the content provider's regional plan may be better processed by a DNS server in a region corresponding to the content provider's regional plan. In this example, the DNS server component 118 may also obtain geographic information from the client directly (such as information provided by the client computing device or ISP) or indirectly (such as inferred through a client computing device's IP address).
In another example, the CDN service provider 106 can attempt to direct DNS queries to DNS servers according to service level criteria. The service level criteria can correspond to service or performance metrics contracted between the CDN service provider 106 and the content provider 104. Examples of performance metrics can include latencies of data transmission between the CDN service provider POPs and the client computing devices 102, total data provided on behalf of the content provider 104 by the CDN service provider POPs, error rates for data transmissions, and the like.
In still a further example, the CDN service provider 106 can attempt to direct DNS queries to DNS servers according to network performance criteria. The network performance criteria can correspond to measurements of network performance for transmitting data from the CDN service provider POPs to the client computing device 102. Examples of network performance metrics can include network data transfer latencies (measured by the client computing device or the CDN service provider 106, network data error rates, and the like).
In accordance with an illustrative embodiment, the DNS server maintains a data store that defines CNAME records for various original URLs. If a DNS query corresponding to a particular original URL matches an entry in the data store, the receiving DNS server component 120 returns a CNAME record as defined in the data store. In an illustrative embodiment, the data store can include multiple CNAME records corresponding to a particular original URL. The multiple CNAME records would define a set of potential candidates that can be returned to the client computing device 102. In such an embodiment, the DNS server component 120, either directly or via a network-based service, can implement additional logic in selecting an appropriate CNAME from a set of possible of CNAMEs. For example, the DNS servers can have logic to determine which CNAME to return for purposes of testing different components or aspects of the CDN service provider 106. Examples of such different aspects can include testing different software application platforms, testing different supported languages, testing different ISPs, and the like. In an illustrative embodiment, each DNS server component 120, 126 maintains the same data stores that define CNAME records, which can be managed centrally by the CDN service provider 106. Alternatively, each DNS server component 120, 126 can have POP specific data stores that define CNAME records, which can be managed centrally by the CDN service provider 106 or locally at the POP 118, 124.
The returned CNAME can also include request routing information that is different from or in addition to the information provided in URL/CNAME of the current DNS query. For example, if the CNAME selection is based on regional plan, a specific regional plan can be identified in the “request_routing_information” portion of the specific CNAME record. A similar approach could be taken to identify service level plans and file management by including a specific identifier in the “request_routing_information” portion of the CNAME record. In another embodiment, request routing information can be found in the identification of a CDN service provider 106 domain different from the domain found in the current URL/CNAME. For example, if the CNAME is based on regional plan, a specific regional plan domain (e.g., “cdnprovider-region1.com”) could be used in the domain name portion of the specific CNAME record. Any additional request routing information can be prepended to the existing request routing information in the current URL/CNAME such that the previous request routing information would not be lost (e.g., serviceplan.regionalplan.cdnprovider.com). One skilled in the relevant art will appreciate that additional or alternative techniques and/or combination of techniques may be used to include the additional request routing information in the CNAME record that is selected by the DNS server component 120.
With reference now to FIG. 5, in an illustrative embodiment, the DNS resolver 108 obtains the CNAME, or other alternative identifier, provided by the receiving DNS server and processes the CNAME. In one aspect, the DNS resolver 108 can process the return information to log or determine performance measurement information, such as a total time from the transmittal of the original DNS query. Additionally, in accordance with network principles, the DNS resolver 108 then transmits a DNS query corresponding to the returned CNAME. As previously discussed with regard to FIG. 4, the DNS query process could first start with DNS queries for the “.” and “com” portions, followed by a query for the “cdnserviceprovider” portion of the CNAME. To the extent, however, that the results of previous DNS queries can be cached (and remain valid), the DNS resolver 108 can utilize the cached information and does not need to repeat the entire process. However, at some point, depending on whether the CNAME provided by DNS server component 120 (FIG. 4) and the previous URL/CNAME share common CDN service provider domains, resolves to a different POP provided by the CDN service provider 106.
As illustrated in FIG. 5, the DNS server component 126 of POP 124 is now authoritative based on the different information in the current CNAME previously provided by the DNS server component 120. As previously described, the DNS server component 126 can then determine whether to resolve the DNS query on the CNAME with an IP address of a cache component that will process the content request or whether to provide another alternative resource identifier selected in the manner described above. In an illustrative embodiment, the DNS server components can utilize a variety of information in selecting a resource cache component. In one example, the DNS server component can default to a selection of a resource cache component of the same POP. In another example, the DNS server components can select a resource cache component based on various load balancing or load sharing algorithms. Still further, the DNS server components can utilize network performance metrics or measurements to assign specific resource cache components. The IP address selected by a DNS server component may correspond to a specific caching server in the resource cache. Alternatively, the IP address can correspond to a hardware/software selection component (such as a load balancer).
Based on the processes illustrated in FIGS. 4 and 5, the CDN service provider 106, DNS resolver 108 or other component can utilize performance measurement information for a variety of purposes. For example, the collected performance measurement information can be utilized to determine an ordered priority of POPs for a particular DNS resolver component 108 or sets of DNS resolver components. In another example, the performance measurement information can be utilized to verify an existing prioritization of POPs for a particular DNS resolver component 108 or sets of DNS resolver components. Still further, the performance measurement information can be combined with other information mapping client computing devices 102 with DNS resolver components 108 to determine prioritized or optimized POPs for client computing devices 102 or groups of client computing devices associated with one or more DNS resolvers 108.
With reference now to FIG. 6, in another embodiment to measure performance measurement after the receipt of content including one or more embedded identifiers (FIG. 3), the client computing device 102 would first transmit a DNS query through its DNS resolver 108 to request an IP address of a computing device corresponding to the unique identifier provided by the CDN service provider 106. The DNS query would be received by the DNS resolver 108 and then transmitted on behalf of the requesting client computing device 102.
As previously described with regard to FIG. 4, by way of example, in accordance with traditional DNS request routing principles, a DNS query for the URL would first include the identification of a DNS server authoritative to the “.” and the “coin” portions of the URL to the DNS resolver 108. The issuance of DNS queries corresponding to the “.” and the “com” portions of a URL are well known and have not been illustrated. After partially resolving the modified URL according to the “.” and “com” portions of the URL, the DNS resolver 108 then issues another DNS query for the resource URL that results in the identification of the DNS server corresponding to the “.cdnserviceprovider” portion of the URL. Specifically, the successful resolution of the “.cdnserviceprovider” portion of the original URL identifies a network address, such as an IP address, of a DNS server associated with the CDN service provider 106. In this embodiment, the IP address can be shared by one or more POPs. Accordingly, the further DNS query to the shared IP address utilizes a one-to-many network routing schema, such as anycast, such that a specific POP will receive the request as a function of network topology. For example, in an anycast implementation, a DNS query issued by a client computing device 102 to a shared IP address will arrive at a DNS server component logically having the shortest network topology distance, often referred to as network hops, from the client computing device. The network topology distance does not necessarily correspond to geographic distance. However, in some embodiments, the network topology distance can be inferred to be the shortest network distance between a client computing device 102 and a POP.
As previously discussed with regard to FIG. 4, the receiving DNS server component 120 obtains the DNS query from the DNS resolver component 108 and processes the DNS query. In an illustrative embodiment, the DNS server component 120 determines that the processing of the DNS query should be, at least in part, used to measure performance of the DNS resolver 108 or other network component. In one embodiment, the DNS query may not correspond to an actual resource that will be delivered to the client computing device 102. Alternatively, the DNS query may correspond to an actual resource provided by the CDN service provider 106 on behalf of the content provider 104. Illustratively, the “additional information” portion of the URL may include information that will be utilized to determine whether the CDN service provider 106 should utilize the DNS query for performance measurement or whether it will be utilized in the determination of the performance measurement. For example, a client computing device may execute a script prior to the generation of the DNS query that modifies the URL to include various identifiers or timing information in the URL.
To facilitate the performance measurement, the receiving POP, POP 118, can obtain information from the DNS query or collect additional information. The collected information can be maintained in the DNS resolver log data store 130. One skilled in the relevant art will appreciate that, typically, a receiving DNS server can resolve DNS queries by identifying an IP address of a cache server component, such resource cache component 122, that will process the request for the requested resource. The selected resource cache component can process the request by either providing the requested resource if it is available or attempting to obtain the requested resource from another source, such as a peer cache server computing device or the origin server 114 of the content provider 104. However, in this illustrative embodiment, as an alternative to selecting a cache server component, the CDN service provider 106 can maintain sets of various alternative resource identifiers that can be utilized for more refined request routing purposes. Additionally, in this embodiment, the alternative resource identifiers can be utilized to measure the performance of the DNS resolver component 108 (or other network components). Specifically, the alternative resource identifiers can be provided by the CDN service provider 106 to the client computing device 102 such that a subsequent DNS query on the alternative resource identifier will resolve to a different DNS server component within the CDN service provider's network. As previously discussed, the alternative resource identifier can correspond to a CNAME.
With reference now to FIG. 7, in an illustrative embodiment, the DNS resolver 108 obtains the CNAME, or other alternative identifier, provided by the receiving DNS server and processes the CNAME. In one aspect, the DNS resolver 108 can process the return information to log or determine performance measurement information, such as a total time from the transmittal and processing of the original DNS query, available bandwidth, packet loss, data throughput, etc. Additionally, in accordance with network principles, the DNS resolver 108 then transmits a DNS query corresponding to the returned CNAME. As previously discussed with regard to FIG. 4, the DNS query process could first start with DNS queries for the “.” and “com” portions, followed by a query for the “.cdnserviceprovider” portion of the CNAME. To the extent, however, that the results of a previous DNS queries can be cached (and remain valid), the DNS resolver 108 can utilize the cached information and does not need to repeat the entire process. However, in this embodiment, at some point, the DNS resolver 108 transmits a DNS query for the “.cdnserviceprovider” utilizing a different network routing schema. Specifically, in an illustrative embodiment, the further DNS query to a shared IP address or unique IP address utilizes a one-to-one network routing schema, such as unicast, such that a specific POP will receive the DNS query.
In this embodiment, the CNAME is selected such that the subsequent DNS query will be received by the same POP utilizing the different network routing schema. Examples of different routing schemas can include the utilization of different communication protocols, such as anycast and unicast. In other examples, the routing schema can include the specification of different communication network paths or the utilization of different ISPs. For example, the IP address of the DNS servers of the CDN service provider may be selected such that the first and second DNS queries (and possibly additional DNS queries) may be transmitted via different communication network ISPs. In another example, a communication protocol, such as the Border Gateway Protocol, can be manipulated to facilitate the transmission of DNS queries along different communication network paths. As illustrated in FIG. 7, the DNS server component 120 of POP 118 is again authoritative based on the information in the current CNAME previously provided by the DNS server component 118. As previously described, the DNS server component 120 can then determine whether to resolve the DNS query on the CNAME with an IP address of a cache component that will process the content request or whether to provide another alternative resource identifier selected in the manner described above. In an illustrative embodiment, the DNS server components can utilize a variety of information in selecting a resource cache component. In one example, the DNS server component can default to a selection of a resource cache component of the same POP. In another example, the DNS server components can select a resource cache component based on various load balancing or load sharing algorithms. Still further, the DNS server components can utilize network performance metrics or measurements to assign specific resource cache components. The IP address selected by a DNS server component may correspond to a specific caching server in the resource cache. Alternatively, the IP address can correspond to a hardware/software selection component (such as a load balancer).
With reference now to FIG. 8, in an alternative to the embodiment illustrated in FIG. 7, the CNAME is selected such that the subsequent DNS query will be received by a different POP utilizing the different network routing schema. Accordingly, as illustrated in FIG. 8, the DNS server component 126 of POP 124 is now authoritative based on the different information in the current CNAME previously provided by the DNS server component 120. As previously described, the DNS server component 126 can then determine whether to resolve the DNS query on the CNAME with an IP address of a cache component that will process the content request or whether to provide another alternative resource identifier selected in the manner described above. In an illustrative embodiment, the DNS server components can utilize a variety of information in selecting a resource cache component. In one example, the DNS server components can default to a selection of a resource cache component of the same POP. In another example, the DNS server components can select a resource cache component based on various load balancing or load sharing algorithms. Still further, the DNS server components can utilize network performance metrics or measurements to assign specific resource cache components. The IP address selected by a DNS server component may correspond to a specific caching server in the resource cache. Alternatively, the IP address can correspond to a hardware/software selection component (such as a load balancer).
Based on the processes illustrated in FIGS. 6, 7 and 8, the CDN service provider, DNS resolver 108 or other component can utilize performance measurement information for a variety of purposes. For example, the collected performance measurement information can be utilized to determine an ordered priority of routing schemas utilized to access particular POPs. In another example, the performance measurement information can be utilized to verify an existing prioritization of POPs for a particular DNS resolver component 108 or sets of DNS resolver components. Still further, the performance measurement information can be combined with other information mapping client computing devices 102 with DNS resolver components 108 to determine prioritized or optimized POPs for client computing devices 102 or groups of client computing devices associated with one or more DNS resolvers 108.
With reference now to FIG. 9, a request routing processing routine 900 implemented by the CDN service provider 106 will be described. One skilled in the relevant art will appreciate that actions/steps outlined for routine 900 may be implemented by one or many computing devices/components that are associated with the CDN service provider 106. Accordingly, routine 900 has been logically associated as being performed by the CDN service provider 106.
At block 902, one of the DNS server components 120, 126 obtains a DNS query corresponding to resource identifier (the “receiving DNS server”). As previously discussed, the resource identifier can be a URL that has been embedded in content requested by the client computing device 102 and previously provided by the content provider 104. Alternatively, the resource identifier can also correspond to a CNAME provided by a content provider DNS server in response to a DNS query previously received from the client computing device 102. At block 904, the receiving DNS server obtains DNS resolver 108 identification information from the DNS query, such as an IP address or other identifier.
At decision block 906, a test is conducted to determine whether the current DNS server is authoritative to resolve the DNS query. In one illustrative embodiment, the DNS server can determine whether it is authoritative to resolve the DNS query if there are no CNAME records corresponding to the received resource identifier (e.g., no additional performance measurement will take place).
If the current DNS server is authoritative (including a determination that the same DNS server will be authoritative for subsequent DNS queries), the current DNS server resolves the DNS query by returning the IP address of a cache server component at block 908. In a non-limiting manner, a number of methodologies for selecting an appropriate resource cache component have been previously discussed. Additionally, as described above, the IP address may correspond to a specific cache server of a resource cache component or generally to group of cache servers.
Alternatively, if at decision block 906, the DNS server is not authoritative, at block 910, the DNS server component selects and transmits an alternative resource identifier. As described above, the DNS server component can utilize a data store to identify an appropriate CNAME as a function of the current DNS query. Additionally, the DNS server component can also implement additional logical processing to select from a set of potential CNAMES. As previously described, in one embodiment, the CNAME may be selected to direct the DNS resolver 108 to a different POP. In another embodiment, the CNAME may be selected to direct the DNS resolver 108 to utilize a different request routing schema, regardless of whether the subsequent CNAME DNS query is directed to the same or different DNS server. At block 912, different DNS server components receive a DNS query corresponding to the CNAME. The routine 900 then returns to decision block 906 and continues to repeat as appropriate.
It will be appreciated by one skilled in the relevant art that there are a number of ways to modify the routing information associated with requests from a class of client computing devices. It will further be appreciated by one skilled in the relevant art that the timing at which performance is monitored and updates to routing information are made can vary.
It will be appreciated by those skilled in the art and others that all of the functions described in this disclosure may be embodied in software executed by one or more processors of the disclosed components and mobile communication devices. The software may be persistently stored in any type of non-volatile storage.
Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.
Any process descriptions, elements, or blocks in the flow diagrams described herein and/or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those skilled in the art. It will further be appreciated that the data and/or components described above may be stored on a computer-readable medium and loaded into memory of the computing device using a drive mechanism associated with a computer-readable medium storing the computer executable components such as a CD-ROM, DVD-ROM, or network interface; further, the component and/or data can be included in a single device or distributed in any manner. Accordingly, general purpose computing devices may be configured to implement the processes, algorithms and methodology of the present disclosure with the processing and/or execution of the various data and/or components described above.
It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

## Claims

1. A computer-implemented system comprising:
a data store for storing performance monitoring information associated with network components associated with client computing device requests for content; and
a computing system in communication with said data store and associated with a service provider, the computing system including a hardware component and operative to:
obtain a first domain name service (DNS) query from a network component responsive to at least one resource identifier, the first DNS query corresponding to a resource associated with the resource identifier, and the network component providing the first DNS query on behalf of a client computing device in accordance with a first network scheme; and
determine an alternative identifier responsive to the first DNS query from the network component, the alternative identifier to cause a second DNS query associated with the resource to be transmitted from the network component to a component associated with the service provider utilizing a second network scheme, and the determination of the alternative identifier being based on additional information provided in a DNS portion of the first DNS query.

2. The system as recited in claim 1, wherein the computing system including the hardware component is further operative to:
determine an ordered priority of network schemes to use to access particular components associated with the service provider, the determination of the ordered priority being based on performance information associated with the first and second DNS queries.

3. The system as recited in claim 1, wherein the computing system including the hardware component is further operative to:
verify an existing prioritization of components associated with the service provider for servicing requests from the network component, the verification of the existing prioritization being based on performance information associated with the first and second DNS queries.

4. The system as recited in claim 1, wherein the resource identifier corresponds to a uniform resource locator of the service provider.

5. The system as recited in claim 1, wherein the alternative identifier references a domain different from a domain associated with the resource identifier.

6. The system as recited in claim 1, wherein the first DNS query is transmitted in accordance with an anycast network scheme.

7. The system as recited in claim 1, wherein the second DNS query is transmitted in accordance with a unicast network scheme.

8. The method as recited in claim 1, wherein the network component corresponds to a DNS resolver component.

9. The system as recited in claim 1, wherein the first network scheme corresponds to a first network path and the second network scheme corresponds to a second network path.

10. The system as recited in claim 1, wherein the first and second DNS queries are obtained by different network components.

11. A computer-implemented method comprising:
obtaining, by a service provider, a first domain name service (DNS) query from a network component responsive to at least one resource identifier, the first DNS query corresponding to a resource associated with the resource identifier, and the network component providing the first DNS query on behalf of a client computing device in accordance with a first network scheme; and
determining, by the service provider, an alternative identifier responsive to the first DNS query from the network component, the alternative identifier to cause a second DNS query associated with the resource to be transmitted from the network component to a component associated with the service provider utilizing a second network scheme, and the determination of the alternative identifier being based on additional information provided in a DNS portion of the first DNS query.

12. The method as recited in claim 11 further comprising determining an ordered priority of network schemes to use to access particular components associated with the service provider, the determination of the ordered priority being based on performance information associated with the first and second DNS queries.

13. The method as recited in claim 11 further comprising verifying an existing prioritization of components associated with the service provider for servicing requests from the network component, the verification of the existing prioritization being based on performance information associated with the first and second DNS queries.

14. The method as recited in claim 11, wherein the resource identifier corresponds to a uniform resource locator of the service provider.

15. The method as recited in claim 11, wherein the alternative identifier references a domain different from a domain associated with the resource identifier.

16. The method as recited in claim 11, wherein the alternative identifier includes a label representative of request routing information identifying the different component associated with the service provider.

17. The method as recited in claim 11, wherein the alternative identifier further includes a label representative of additional information associated with the client computing device.

18. The method as recited in claim 11, wherein the first DNS query is transmitted in accordance with an anycast network scheme.

19. The method as recited in claim 11, wherein the second DNS query is transmitted in accordance with a unicast network scheme.

20. The method as recited in claim 11, wherein the network component corresponds to a DNS resolver component.

21. The method as recited in claim 11, wherein the first network routing scheme corresponds to a first network path and the second network routing scheme corresponds to a second network path.

22. The method as recited in claim 11, wherein the first and second DNS queries are obtained by different network components.