confused with domain name in dhcp and ip domain name what do they do ?

[dolanduck.]

i need help understanding what IP domain-name does like what is its purpose and on domain name in dhcp whats the purpose of putting cisco.com or random name.

[Giuseppe Larosa · Accepted solution]

Hello waffi1234,

with ip domain-name global command you are telling the router on which domain it is the device itself.

The device will consider itself as hostname.mydomain.com instead of only hostname.

Commands under ip dhcp pool are commands to provide info as DHCP options to DHCP clients.

To make an important example you need to set an ip domain-name in order to generate RSA keys to be used for SSH sessions on VTY lines.

Hope to help

Giuseppe

[dolanduck.]

so for the ip domain name for ssh. for example if i am trying to ssh to my router i can use cats.com to ssh to it?

[Giuseppe Larosa]

Hello waffi1234,

I'm sorry I have been not so clear before.

You need to configure the ip domain-name before issuing the crypto key generate rsa command.

The reason is that the RSA keys will get a name from the hostname + domain.name.

when you want to SSH to your device you need to use an SSH client like Putty and use a router IP address as the destination address.

You can SSH to hostname.cats.com if you have registered the DNS record   (A record for IPv4) with your DNS server.

Otherwise you need to still SSH to the router's IP address.

Hope to help

Giuseppe