Adding DNS records

I’m trying to understands DNS a bit better.

When we add a pc to our network we include a domain in the network properties, i.e. nodename.mydomain.ac.uk.

I can then ping this & get a reply with the domain included, however, when I check the primary DNS server there is no record for the new node.

I know WINS is dynamic & DNS is static but I thought maybe the PC was sending an update to the DNS server.

QUERY:

Is the reply to the ping actually from WINS/Netbios & if so why is the domain included.

If it is dns then why is there no record in the primary dns server.

Any advice gratefully accepted

P.S. We are running NT 4 servers, static IP addressing, one primary dns and several secondary servers.

Thanks