No. You only need to know the name server IP if the name server does not exist in the registry. If your ISP or web hosting provider has given you the name server it is safe to say that the name server already exists in the registry.

If the name server you want to delegate to does NOT exist in the registry and the name server is an Enetica domain you can log into that domain via domain management and click on "Hostnames" and add the name servers (also known as hosts) with their corresponding IP address.

This will create the name server in the registry.