(DNS, in fact, is a classic example of a highly distributed database where each node maintains a relatively small amount of data.) It is hierarchical as well for the DNS name intronetworks.cs.luc.edu the levels of the hierarchy are Due to the much larger response sizes, TCP is often necessary for DNSSEC ( 22.12 DNSSEC).ĭNS is distributed, meaning that each domain is responsible for maintaining its own DNS servers to translate names to addresses.

Most DNS traffic today is over UDP, although a TCP option exists. While a workstation can use TCP/IP without DNS, users would have an almost impossible time finding anything, and so the core startup configuration of an Internet-connected workstation almost always includes the IP address of its DNS server (see 7.10 Dynamic Host Configuration Protocol (DHCP) below for how startup configurations are often assigned). The AAAA record type is used for IPv6 addresses, and, internally, the NS record type is used to identify the “name servers” that answer DNS queries. While DNS supports a wide variety of queries, for the moment we will focus on queries for IPv4 addresses, or so-called A records.

DNS also makes it easy to move services from one server to another with a different IP address as users will locate the service by DNS name and not by IP address, they do not need to be notified.

Instead of 162.216.18.28, a user can simply enter intronetworks.cs.luc.edu, and DNS will take care of looking up the name and retrieving the corresponding address. It is DNS that permits users the luxury of not needing to remember numeric IP addresses. The Domain Name System, DNS, is an essential companion protocol to IPv4 (and IPv6) an overview can be found in RFC 1034.

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