Administrator Guide

Resolution of Host Names
Domain name service (DNS) maps host names to IP addresses. This feature simplies commands such as Telnet and FTP by allowing you
to enter a name instead of an IP address.
Dynamic resolution of host names is disabled by default. Unless you enable the feature, the system resolves only host names entered into
the host table with the ip host command.
In a dual stack setup, the system sends both A ( for IPv4 — RFC 1035) and AAAA ( for IPv6 — RFC 3596) record requests to a DNS
server even if you congure only the ip name-server command.
Name server, Domain name, and Domain list are VRF specic. The maximum number of Name servers and Domain lists per VRF is six.
Enabling Dynamic Resolution of Host Names
By default, dynamic resolution of host names (DNS) is disabled.
To enable DNS, use the following commands.
• Enable dynamic resolution of host names.
CONFIGURATION mode
ip domain-lookup
• Specify up to six name servers.
CONFIGURATION mode
ip name-server ip-address [ip-address2 ... ip-address6]
The order you entered the servers determines the order of their use.
Example of the show hosts Command
To view current bindings, use the show hosts command.
Dell>show host
Default domain is force10networks.com
Name/address lookup uses domain service
Name servers are not set
Host Flags TTL Type Address
-------- ----- ---- ---- -------
ks (perm, OK) - IP 2.2.2.2
patch1 (perm, OK) - IP 192.68.69.2
tomm-3 (perm, OK) - IP 192.68.99.2
gxr (perm, OK) - IP 192.71.18.2
f00-3 (perm, OK) - IP 192.71.23.1
Dell>
To view the current conguration, use the show running-config resolve command.
Specifying the Local System Domain and a List of
Domains
If you enter a partial domain, the system can search dierent domains to nish or fully qualify that partial domain.
A fully qualied domain name (FQDN) is any name that is terminated with a period/dot. The system searches the host table rst to resolve
the partial domain. The host table contains both statically congured and dynamically learnt host and IP addresses. If the system cannot
resolve the domain, it tries the domain name assigned to the local system. If that does not resolve the partial domain, the system searches
the list of domains congured.
To congure a domain name or a list of domain names, use the following commands.
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IPv4 Routing