Non-authoritative answer

Non-authoritative answer

Post by Coolpea » Sun, 16 Sep 2001 19:24:16



Recently I found that some server cannot send e-mail to my server. Then
I use "nslookup" to check the name and address of my server. I found
that
except the command information such as ns server information, ns server
address,
my server's name and address, there is one more sentence before my
server's
name and address:

Non-authoritative answer:

Can anyone tell me what happen of it? Thanks.

 
 
 

Non-authoritative answer

Post by Marc » Sun, 16 Sep 2001 22:09:59


Hi

Quote:> Recently I found that some server cannot send e-mail to my server. Then
> I use "nslookup" to check the name and address of my server. I found
> that
> except the command information such as ns server information, ns server
> address,
> my server's name and address, there is one more sentence before my
> server's
> name and address:

> Non-authoritative answer:

> Can anyone tell me what happen of it? Thanks.

Yes. The program nslookup connected to a name server (say A) to ask for the
information. Obviously, it didn't ask the specific DNS server (say B) that
hosts the information of your computer. So to find this information, server
A has to ask server B about this information. But once it has obtained the
information, it caches it to minimize traffic.
By saying "Non-authoritative answer" server A is indicating to you that it
got this information out of its cache instead of querying server B.

Marco

 
 
 

Non-authoritative answer

Post by Ian Northeas » Mon, 17 Sep 2001 22:16:42



> Hi

> > Recently I found that some server cannot send e-mail to my server. Then
> > I use "nslookup" to check the name and address of my server. I found
> > that
> > except the command information such as ns server information, ns server
> > address,
> > my server's name and address, there is one more sentence before my
> > server's
> > name and address:

> > Non-authoritative answer:

> > Can anyone tell me what happen of it? Thanks.

> Yes. The program nslookup connected to a name server (say A) to ask for the
> information. Obviously, it didn't ask the specific DNS server (say B) that
> hosts the information of your computer. So to find this information, server
> A has to ask server B about this information. But once it has obtained the
> information, it caches it to minimize traffic.
> By saying "Non-authoritative answer" server A is indicating to you that it
> got this information out of its cache instead of querying server B.

Indeed, and not a problem if the server being queried is not one of the
servers which should be authoritative for the domain in question. If it
is however, it does mean there is an error. Some versions of bind (<9)
would react to errors in zone files by loading the zones and answering
queries, but answering non-authoritatively. This causes further problems
like failure of slave zone transfers. This in turn could cause the sort
of problem the OP is having.

To the OP - if you continue to have trouble then some real names would
help. I assume the problem domain is not "hongkong.com".

Regards, Ian

 
 
 

1. Name server always gives non-authoritative answer

ns.cs.tsinghua.edu.cn is the primary name server of domain
cs.tsinghua.edu.cn, but all answers to name->IP requests
from it are always non-authoritative.  IP->name is good.

Who can tell me what are the common reasons for this problem?
Any help will be appreciated.  Thanks in advance.

The following is an example:

$ nslookup - ns.cs.tsinghua.edu.cn
Default Server:  ns.cs.tsinghua.edu.cn
Address:  166.111.80.200

Server:  ns.cs.tsinghua.edu.cn
Address:  166.111.80.200

Non-authoritative answer:
cs.tsinghua.edu.cn      nameserver = ns.cs.tsinghua.edu.cn
cs.tsinghua.edu.cn      nameserver = ns.tsinghua.edu.cn
cs.tsinghua.edu.cn      preference = 10, mail exchanger =
ns.cs.tsinghua.edu.cn
cs.tsinghua.edu.cn      preference = 0, mail exchanger =
ns.cs.tsinghua.edu.cn
cs.tsinghua.edu.cn
        origin = ns.cs.tsinghua.edu.cn
        mail addr = hostmaster.cs.tsinghua.edu.cn
        serial = 96010520
        refresh = 10800 (3 hours)
        retry   = 3600 (1 hour)
        expire  = 432000 (5 days)
        minimum ttl = 86400 (1 day)

Authoritative answers can be found from:
ns.cs.tsinghua.edu.cn   internet address = 166.111.80.200
ns.tsinghua.edu.cn      internet address = 166.111.8.11

Regards,
Wang Xianzhu

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