Domain Name System
The Domain Name System (DNS) is a
hierarchical naming system that assigns a name (such as a company name) to an Internet
entity to represent the real IP address of the entity. An entity can be a gateway router and
is referred to as a domain.
A domain name (for example, extreme.router.com)
can be used in place of an IP address for certain operations such as IP pings, trace
routes, and Telnet management connections to the router. A domain name is easier to
remember than all of the numbers in an IP address. DNS has several components.
- DNS server: A DNS server stores the
information about a DNS domain. DNS servers are a key element of DNS because they
respond to queries against its database. When a DNS domain is defined on this device
to recognize all hosts in that domain, this device automatically appends the
appropriate domain to the host address and forwards it to the DNS server.
- DNS resolver: In a Layer 2 or Layer 3 device,
the DNS resolver sends and receives queries to and from the DNS server on behalf of
a client. You can create a list of domain names that can be used to resolve host
names. This list can have more than one domain name. When a client performs a DNS
query, all hosts in the domains in the list can be recognized and queries can be
sent to any domain on the list. After you define a domain name, the device
automatically appends the appropriate domain to a host and forwards it to the DNS
servers for resolution.
- DNS gateway addresses: Gateway IP
addresses that are assigned to the device enable clients that are attached to the
device to reach DNS.
