Getting hold of serial numbers

[Jonathan de Boyne Pollard]

PE> The DNS and the WHOIS databases are not the same thing, and there
PE> is no intrinsic link between the two.

BM> Why do people keep saying this?

Because they don't know enough to actually instead say:

Don't look up a list of content DNS servers to query using NICNAME.  
Your NICNAME client might print the response from an inappropriate 
NICNAME server (especially if the domain name is in a GTLD where many 
NICNAME clients will print the response from the registrar's NICNAME 
server rather that the response from the registry's NICNAME server, the 
latter being the appropriate one here), some NICNAME servers (especially 
"smart" proxies) derive the nameserver lists in unexpected ways, the 
NICNAME data are not necessarily as current as the DNS data, and it's a 
lot easier (given that you are just about to make *other* DNS lookups 
and so have the tools ready to hand) to just look up the DNS data directly.

BM> The delegations in the GTLD servers come from the registries, and
BM> the registrars provide WHOIS servers that work off the same data
BM> that they send to the registry.

... and the registries themselves _also_ provide NICNAME servers that 
work off a database directly derived from the actual registry database 
itself.

BM> If you ever see a difference between WHOIS and a delegation, it's
BM> either because you caught it during a change window (the WHOIS
BM> database has updated, but the changes haven't propagated to the GTLD
BM> servers) or something is broken in the process of feeding data from
BM> registrar to registry to DNS.

The change window is the other way around, usually.  Registries will 
update the DNS databases (that their content DNS servers publish) from 
the registry database more frequently than they will update the NICNAME 
database (that their NICNAME servers publish) from the registry 
database.  For example:  Verisign and PIR update their DNS databases 
every few minutes, but only update their NICNAME databases a couple of 
times per day.