glue record

Barry Margolin barmar at alum.mit.edu
Wed May 13 07:50:28 UTC 2009


In article <gudtlf$1u4n$1 at sf1.isc.org>,
 "Tech W." <techwww at yahoo.com.cn> wrote:

> --- On Wed, 13/5/09, Stephane Bortzmeyer <bortzmeyer at nic.fr> wrote:
> 
> > 
> > Glue was sent back since wanadoo.fr's name servers are
> > under
> > wanadoo.fr .
> 
> 
> Ok please see dig info below.
> if I understand for it correctly, gdpu.cn is not under b.dns.cn, why b.dns.cn 
> returns glues?

How would you look up anything in this domain if it didn't return glue?  
To look up anything.gdpu.cn, you have to ask dns1.gdpu.cn or 
dns2.gdpu.cn.  This requires you to find the IP of dns{1,2}.gdpu.cn, 
which you can only do by asking dns{1,2}.gdpu.cn.  The glue keeps you 
from getting stuck in this loop.

> 
> Thanks.
> 
> 
> # dig gdpu.cn ns @B.DNS.cn
> 
> ; <<>> DiG 9.5.0-P2 <<>> gdpu.cn ns @B.DNS.cn
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53380
> ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 2
> ;; WARNING: recursion requested but not available
> 
> ;; QUESTION SECTION:
> ;gdpu.cn.                       IN      NS
> 
> ;; AUTHORITY SECTION:
> gdpu.cn.                21600   IN      NS      dns1.gdpu.cn.
> gdpu.cn.                21600   IN      NS      dns2.gdpu.cn.
> 
> ;; ADDITIONAL SECTION:
> dns1.gdpu.cn.           21600   IN      A       219.136.229.41
> dns2.gdpu.cn.           21600   IN      A       219.136.229.42

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE don't copy me on replies, I'll read them in the group ***



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