If you are just changing the nameserver (eg. ns1.yourhost.tld , ns2.yourhost.tld) - no need for ip address.
If you are creating any child nameserver (eg. ns1.yourdomain.tld, ns2.yourdomain.tld) - then you need to add ip address.
To check the current nameserver of your domain check here: http://intodns.com/
In most cases, when you change nameserver, it takes time to propagate (usually within 15 minutes to 24 hours for some cases too.)