about the reference

[Lyle Giese]

On 07/01/11 03:47, Jeff Peng wrote:
> Hello,
>
> Please see this reference:
>
> $ dig mydots.net @j.gtld-servers.net
>
> ;<<>>  DiG 9.4.2-P2.1<<>>  mydots.net @j.gtld-servers.net
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41902
> ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 2
> ;; WARNING: recursion requested but not available
>
> ;; QUESTION SECTION:
> ;mydots.net.                    IN      A
>
> ;; AUTHORITY SECTION:
> mydots.net.             172800  IN      NS      ns1.dnsbed.com.
> mydots.net.             172800  IN      NS      ns2.dnsbed.com.
>
> ;; ADDITIONAL SECTION:
> ns1.dnsbed.com.         172800  IN      A       74.117.233.4
> ns2.dnsbed.com.         172800  IN      A       204.152.196.108
>
> ;; Query time: 196 msec
> ;; SERVER: 192.48.79.30#53(192.48.79.30)
> ;; WHEN: Fri Jul  1 16:23:05 2011
> ;; MSG SIZE  rcvd: 106
>
>
>
> j.gtld-servers.net gives the reference info about the domain mydots.net.
> It says the dns servers for mydots.net is ns[1-2].dnsbed.com, following with two NS's IP addresses.
>
>
> My question is, when other BIND Cache get this reference, will it use the IP addresses directly?
> Or will it use the IP addresses get from the authoritative server?
>
> I ask this because, when the IP addresses get from reference, are different from the ones get from the authoritative server, what will be happened?
>
> Thanks for your kind helps.

Jeff,
Think about this scenerio:

example.com uses ns1.example.com and ns2.example.com for it's name 
servers(legal and proper).

If the resolver did not use the glue records presented from the root 
servers, how would the resolver find www.example.com?

When you register name servers, these are called glue records.  The info 
in the additional section, comes from those glue records.

In your scenerio, the results will be unpredicatable and random. 
Sometimes it will work and sometimes it won't work.  It's important that 
the glue records be correct.

Lyle Giese
LCR Computer Services, Inc.