Unable to register X-lite

I am not able to register x-lite with domain name in the request URI but I am able to register it if I put IP address.

Could you help me on this?

Does your “domain name” resolve to your “IP address” ?

ping -c 5 “IP address”

should look much like

ping -c 5 “domain name”

from where your x-lite box is, does it ?.

Yes… I am able to resolve the DNS.