[Pdns-users] [Fwd: Re: DiG: Hopefully Final Thoughts..]
b.candler at pobox.com
Mon Feb 20 18:16:14 UTC 2017
On 20/02/2017 00:38, stancs3 wrote:
> I have attached the remaining thing I cannot resolve (no pun).
> 1. The test above the ===== line is:
> Recursor listening on port 53, forwarding to auth server listening on
> port 5300.
> Dig of NS replies with no Additional section.
> Dig of ns1 replies with the A record.
> 2. The test below the ===== line is:
> No recursor, auth server listening on port 53.
> Dig of NS replies with Additional section showing the A records for
> both NSs.
This is correct behaviour.
The "additional" section is for glue records, and they are only needed
for a resolver talking to an authoritative server, and only in a special
circumstance. They solve the chicken-and-egg problem: if you are
resolving a name within domain EXAMPLE.COM, and the delegation is to
NS1.EXAMPLE.COM, then you need to send the query to NS1.EXAMPLE.COM. But
to send a packet, you need an address to send it to. And in order to
find the address of NS1.EXAMPLE.COM you need to talk to the nameservers
The glue records give a hint as to what addresses to try, when the
delegation is to a nameserver whose name is within the zone being queried.
However, when a client is talking to a resolver, it does not need to see
glue. It just sees the answer (or lack of answer). It's the resolver's
job to contact authoritative nameserver(s) on its behalf.
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