Hi Hussein,
I think the wikipedia page is a good start:
The most common use for using the “ip domain-name” command is probably SSH. However it’s also used sometimes for certificates.
To give you an idea, here’s an example where I used certificates for the anyconnect VPN on an ASA firewall:
https://networklessons.com/security/cisco-asa-anyconnect-self-signed-certificate/
Rene