State Policy state - Enable (default) - Disabled Level Policy - Server - Zone Processing order Once a query is classified by level and applies on, the server finds the first policy for which the query matches the criteria and applies it to query - Numeric value - Unique value per policy containing the same level and applies on value Action Action to be performed by DNS server - (default for zone level) - Deny (default on server level) - Ignore Criteria Policy condition (AND/OR) and list of criterion to be met for policy to be applied - Condition operator (AND/OR) - List of criteria (see the criterion table below) List of zone scopes and weighted values per scope. Weighted values are used for - List of zone scopes (by name) and weights
load balancing distribution. For instance, if this list includes datacenter1 with a weight of 3 and datacenter2 with a weight of 5 the server will respond with a record from datacentre1 three times out of eight requests Note Server level policies can only have the values Deny or Ignore as an action. The DNS policy criteria field is composed of two elements: Name values Client Subnet Transport protocol used in the Possible entries are UDP and TCP - - resolves to true if the subnet is identified as either Spain or France - NE,Canada,Mexico - resolves to true if the client subnet is any subnet other than Canada and Mexico Transport Protocol Transport protocol used in the query. Possible entries are UDP and TCP - EQ,TCP - EQ,UDP Internet Protocol Network protocol used in the - EQ,IPv4 - EQ,IPv6
Possible entries are IPv4 and IPv6 Server Interface IP address IP address for the incoming DNS server network interface - EQ,10.0.0.1 - EQ,192.168.1.1 FQDN FQDN of record in the query, with the possibility of using a wild card - EQ,www.contoso.com - resolves tot rue only the if the query is trying to resolve the www.contoso.com FQDN - EQ,*.contoso.com,*.woodgrove.com - resolves to true if the query is for any record ending in contoso.comORwoodgrove.com Query Type Type of record queried (A, SVR, TXT) - EQ,TXT,SRV - resolves tot rue if the query is requesting a TXT OR SRV record - EQ,MX - resolves tot rue if the query is requesting an MX record Time of Day Time of day the is received - EQ,10:00-12:00,22:00-23:00 - resolves tot rue if the query is received between 10 AM and noon, OR between 10PM and 11PM Using the table above as a starting point, the table below could be used to define a criterion that is used to match queries for any type of records but SRV records in the contoso.com domain coming from a client in the 10.0.0.0/24 subnet via TCP between 8 and 10 PM through interface 10.0.0.3: Name Value Client Subnet EQ,10.0.0.0/24 Transport Protocol EQ,TCP Server Interface IP address EQ,10.0.0.3 FQDN EQ,*.contoso.com Query Type NE,SRV Time of Day EQ,20:00-22:00
For more information, see . You have now successfully created a DNS policy that provides application load balancing across Web servers in three different datacenters. You can create thousands of DNS policies according to your traffic management requirements, and all new policies are applied dynamically - without restarting the DNS server - on incoming queries. To add geo-location awareness to application load balancing, see . Use DNS Policy for Application Load Balancing With Geo-Location Awareness You can use this topic to learn how to configure DNS policy to load balance an application with awareness. The previous topic in this guide, , uses an example of a fictional company - Contoso Gift Services - which provides online gifting services, and which has a Web site named contosogiftservices.com. Contoso Gift Services load balances their online Web application between servers in North American datacenters located in Seattle, WA, Chicago, IL, and Dallas, TX. Note It is recommended that you familiarize yourself with the topic before performing the instructions in this scenario. This topic uses the same fictional company and network infrastructure as a basis for a new example deployment that includes geo-location awareness. In this example, Contoso Gift Services is successfully expanding their presence across the globe. Similar to North America, the company now has web servers hosted in European datacenters. Contoso Gift Services DNS Administrators want to configure application load balancing for European datacenters in a similar manner to the DNS policy implementation in the United States, with application traffic distributed among Web servers that are located in Dublin, Ireland, Amsterdam, Holland, and elsewhere. DNS Administrators also want all queries from locations in the world distributed equally between all of their datacenters. In the next sections you can learn how to achieve similar goals to those of the Contoso DNS Administrators on your own network. How to Configure Application Load Balancing with Geo-Location Awareness The following sections show you how to configure DNS policy for application load balancing with geo-location awareness. Important The following sections include example Windows PowerShell commands that contain example values for many parameters. Ensure that you replace example values in commands with values that are appropriate for your deployment before you run these commands. Create the DNS Client Subnets You must first identify the subnets or IP address space of the North America and Europe regions.