3Com 4007, Implementation Manual, Page: 392 / 684

392 C
HAPTER
16: IP R
OUTING
Domain Name
System (DNS)
The Domain Name System (DNS) client allows you to specify a hostname
rather than an IP address when you perform various operations (for
example, when you use
ping
or
traceRoute
to contact an IP station).
With DNS, you can specify one or more name servers that are associated
with a domain name. Each name server maintains a list of IP addresses
and their associated host names. When you use
ping
or
traceRoute
with
a hostname, the DNS client attempts to locate the name on the name
servers that you specify. When the DNS client locates the name, it resolves
it to the associated IP address.
You can resolve an IP address to a host name or a host name to an IP
address on a name server. Enter either the host name or the IP address;
the DNS client displays the pair.
Important
Considerations
When you set up DNS servers on your LAN, remember the following:
■
Always set up more than one DNS name server (a primary and
secondary server) so that the lookup service does not have a single
point of failure.
■
If your ISP changes the Classes of Internetwork Service, change the
DNS settings on each host that the ISP services.
See UNIX Network File System (NFS) documentation for information
about how to create and maintain lists of domain names and IP addresses
on the name servers.
See Chapter 17 and also the Command Reference Guide , for information
about how to use
ping
and
traceRoute
.