Let's say you have domain.com registered through a certian domain register - you also have the nameservers of ns1.domain.com and ns2.domain.com hooked up etc.

When you transfer that domain to another register, what happens to the current nameservers?

I suppose they have to be re-registered at the new domain register. Is there any propagation issues that would come into play here in respect to these nameservers?

Just curious. :)

Nameservers need to be Registered at the same Registrar as the Domain name. If both have already propagated and working fine, changing Registrars should not effect either one -- as far as working correctly.

With some Registrars though, you cannot register the Nameservers until the Domain name has been transferred to them. This will, of course, cause some downtime. If that is the case with a particular Registrar, one needs to watch constantly so that, once the Domain name has been transferred the Nameservers can be Registered. Downtime is approx. 2 - 12 hrs in this type situations.

An alternative to prevent downtime:

use another domain and register the nameservers the same way. Thus mirroring the original ones. Change the NS on the domain that will be transferred. Transfer and re-register them. And then change. This should cause no downtime (in theory... but #%*$ happens sometimes).

From Enom's help files:
"If I transfer my domain to or from eNom will I have to create my nameservers again? Is there down time when I transfer my domains.

No, the nameservers are registered with the Registry. When the domain transfers, all information is retained with the domain and there is no down time"

Thanks for the info. :)