Different behaviour for different TLDs?

[Kevin Darcy]

Konrad Lienhard wrote:

>Hello
>
>I created a subdomain (with separate dns server responsible for it)
>However I have a problem with it. I narrowed it down to the problem that the
>TLD's for .com are responding different than e.g. the TLD for .ch:
>
>(merapi.switch.ch is a TLD for .ch)
>--------------------------------
>  
>
>>migze020.migros.ch
>>    
>>
>Server:  merapi.switch.ch
>Address:  130.59.211.10
>
>Name:    migze020.migros.ch
>Served by:
>- migze020.migros.ch
>          193.5.175.194
>          migros.ch
>- migze030.migros.ch
>          193.5.175.195
>          migros.ch
>---------------------------------
>(b.gtld-servers.net is a TLD for .com)
>
>  
>
>>ns.swisscom.com
>>    
>>
>Server:  b.gtld-servers.net
>Address:  192.33.14.30
>
>Non-authoritative answer:
>Name:    ns.swisscom.com
>Address:  138.190.1.12
>---------------------------------
>
>So it seems that the .com TLD are caching the ip's of the different
>domainservers. (I know they have to know these ip's but to my understanding
>the answer from the .ch TLD is "more" correct because a TLD should only
>delegating and not answering directly.
>
>Why am I writing all this you may ask. Well I created a subdomain (with
>separate dns servers) and I recently had to change the ip of these dns
>servers responsible for the subdomain. The old ips however seems to bee
>"glued" in the TDL's. If I ask a fresh booted dns server directly what the
>ip of my subdomain nameserver is (e.g. ns.subdomain.domain.com) I get the
>OLD ip! And it's been months since the change so I don't think it has to do
>with caching. Why is that so, and how can I change these old entries?
>If I first ask some dns server for ns.subdomain.domain.com and then for
>www.subdomain.domain.com  I get a failure, because ns.subdomain.domain.com
>is cached wrong. If I directly ask some dns server for
>www.subdomain.domain.com and then for ftp.subdomain.domain.com I get an
>answer because the delegation is then working correct.
>
Well technically it's not considered "caching" but yes, each TLD zone 
contains a copy of the A record(s) for every delegated nameserver which 
happens to also have its name in the same TLD. If a .com subzone is 
delegated to one or more nameservers in the .com domain, then there must 
be corresponding A records in the .com zone itself (otherwise resolution 
would get in this chicken-and-egg situation of not being able to resolve 
anything in a zone because it cannot resolve the names of the 
nameservers for the zone, and so on and so on and so on).

For gTLDs like .com, one would usually get these "glue" records updated 
through one's registrar.

                                                                         
                              - Kevin