When researching where your DNS is hosted can be confusing if the nameservers own domain names to not match the hosting companies names. I am sure GoDaddy have their reasons not to use ns??.godaddy.com etc. So here is a list, if you have any to add, please let me know.

GoDaddy
*.domaincontrol.com

Rackspace Cloud services
*.stabletransit.com

enom.com
*.name-services.com

HostGator
*.websitewelcome.com

Powweb.com
*.yourhostingaccount.com

Domainbox.com
(Domainmonster & Mesh Digital)
*.hosteurope.com

AMHmhosting.com
*.guardedhost.com
*.guardeddns.net

NameCheap.com
*.registrar-servers.com

MelbourneIT.com.au
*.privatedns.com

FastHosts / UKReg
*.livedns.co.uk

ResellerClub.com
*.orderbox-dns.com

EZPZhosting.com
*.thewebhostserver.com

Enom.com
*.name-services.com

Strato.de
*.rzone.de