Opinion ID: 784889
Heading Depth: 4
Heading Rank: 1

Heading: What the domain name system is and how it works10

Text: 79 The Internet is comprised of numerous interconnected communications and computer networks connecting a wide range of end-users to each other. See Reno v. Am. Civil Liberties Union, 521 U.S. 844, 849, 117 S.Ct. 2329, 138 L.Ed.2d 874 (1997). Every end-user's computer that is connected to the Internet is assigned a unique Internet Protocol number (IP address), such as 123.456.78.90, that identifies its location ( i.e., a particular computer-to-network connection) and serves as the routing address for email, pictures, requests to view a web page, and other data sent across the Internet from other end-users. 11 This IP address routing system is essential to the basic functionality of the Internet, in a similar fashion as mailing addresses and telephone numbers are essential to the functionality of the postal service and telecommunications system. 80 A domain name is an alphanumeric text representation (often a word) that identifies a numerical IP address, thus making it easier to remember. While every end-user's computer connected to the Internet is assigned an IP address, not every IP address has a corresponding domain name. Instead, a domain name is associated with a particular IP address (or group of IP addresses) only when an end-user registers the domain name. The primary purpose of domain names is to mak[e] it easier for users to navigate the Internet; the real networking is done through the IP numbers. PGMedia, Inc. v. Network Solutions, Inc., 51 F.Supp.2d 389, 408 (S.D.N.Y.1999), aff'd sub nom. Name.Space, Inc. v. Network Solutions, Inc., 202 F.3d 573 (2d Cir.2000). Domain names consist of various segments separated by periods, such that [t]he left-to-right string of name components proceeds from the most specific to the most general, that is, the root of the tree, ..., is on the right. Rony & Rony, The Domain Name Handbook, at 105 (quoting Zaw-Sing Hu & Jon Postel, The Domain Naming Convention for Internet User Applications, RFC 819 (Aug.1982), available at http://www.ietf.org/rfc/rfc0819.txt?number =819). The Top Level Domain (TLD) refers to the final segment of the name ( i.e., the .gov in www.uscourts.gov). There are three-letter, general purpose TLDs (gTLDs), such as .com, .edu, .gov, and .org, as well as two-letter country-code TLDs (ccTLDs) that are available to end-users in particular geographic/political locations. The Second Level Domain (SLD) refers to the second-to-last segment of the web address ( i.e., the uscourts in www.uscourts.gov) and generally corresponds to an organization. 12 These segments each indicate a particular level within a hierarchical database. See Name.Space, Inc. v. Network Solutions, Inc., 202 F.3d 573, 577 (2d Cir. 2000). This hierarchical database, which maps domain names to IP addresses, is distributed across multiple computers that manage particular parts (or zones) of the database and are openly accessible via the Internet. The information maintained by each of these computers is stored in what is commonly referred to as the zone file. Rony & Rony, The Domain Name Handbook, at 61-62. Generally, Internet service providers (ISPs) 13 utilize domain name servers to translate domain names into numerical IP addresses, based on (1) queries to Root, TLD and SLD name servers, 14 or (2) cached data obtained from those servers, which is typically kept for the web sites requested most frequently by their end-users. See Froomkin, Wrong Turn in Cvberspace, 50 Duke L.J. at 38-39, 44. Essentially, when an end-user types a domain name into her browser, for example, her ISP receives it and, after translating it through the domain name server, forwards a request for data to the IP address corresponding to the domain name the end-user typed in. 15 The recipient of that request may then respond by sending the requested data to the requestor's IP address. See, e.g., Thomas v. Network Solutions, Inc., 176 F.3d 500, 503-04 (D.C.Cir.1999) (describing the process of accessing bettyandnicks.com); Rony & Rony, The Domain Name Handbook, at 72-74.