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    Cisco: Configure DNS Server(s) & Search Domains For Name Resolution

    Posted on 2 mins

    Cisco Networking Cisco IOS

    Table of Contents

    Summary

    Notes for configuring DNS servers and search domains for name resolution on Cisco switches.

    Configure Search Domain

    Connect to the console or login remotely to the switch using SSH. Go into the configuration prompt using the following command.

    configure terminal

    Configure the domain name or search domain that will assist the switch with resolving hosts in the domain it resides in. This is useful if full name resolution is needed without having to type out the fully qualified domain name for the device every time.

    ip domain-name lab.example.org

    Configure DNS Server

    Next I need to add the new name/DNS servers IP address to the switches configuration. This is points to the server or device that hosts the DNS services locally within the lab network so the switch can resolve names to IP addresses.

    ip name-server 192.168.1.51

    Show the running configuration to confirm. Should be able to see the following. This provides the search domain and the DNS server.

    !
ip domain-name lab.example.org
ip name-server 192.168.1.51

    Testing

    Testing is always a good option. To test fully qualified domain name resolution I decided to use the pint command and the full name of the internal DNS server.

    ping lab-inf-01.lab.example.org

    Based on the output below. It looks like it resolves the name of the server to the correct IP address. Then returns a successful pong.

    Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/11 ms

    To test the configuration related to the search domain configuration I just used the host name for the internal DNS server using ping.

    ping lab-inf-01

    Looks like this also resolved the correct name to it’s respective IP address and was able to reach it with no issue.

    Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/11 ms

    Based on the test from the results above. Looks like everything is working as expected.

    Saving Configuration

    When that’s configured, tested, and working. Copy the running configuration of the switch to the startup-config. If no one knows how to do this. There’s a link for that.