does not answer queries over tcp and udp in name sever(centos)

SarahGurung · 04-04-2012, 03:27 AM

Well online dns test shows that the following :

Code:

Name server ns0.x.com (xxx.xxx.xxx.x) does not answer queries over UDP.

The name server failed to answer queries sent over UDP. This is probably due to the name server not correctly set up or due to misconfigured filtering in a firewall.

Name server ns0.x.com (xxx.xxx.xxx.x) does not answer queries over TCP.

The name server failed to answer queries sent over TCP. This is probably due to the name server not correctly set up or due to misconfgured filtering in a firewall. It is a rather common misconception that DNS does not need TCP unless they provide zone transfers - perhaps the name server administrator is not aware that TCP usually is a requirement.

So can anyone tell me what does that mean and what should be done?Actually ns0 is used for zone transfer only,doe real dns purpose other dns server(ns1 an dns2) is used and that doesnt show sch error.

However ns3 show that error but with tcp...

Therefore can anyone help me on this or give ay idea or suggestion?

lithos · 04-04-2012, 04:37 AM

well,

since you don't specify which OS and BIND you are running on your server (if I recall from my memory you previously asked for CentOS help @ LQ)
you should first configure your server's BIND (DNS) settings for that domain you are authoritative (you control it's IP addresses).

The first few guides in google search provide these:
- DNS server install/configure BIND
- BIND server config CentOS 6
- how-to configure chroot BIND CentOS 6

then you will need to set firewall to allow port 53 UDP to let it through.

good luck

lithos · 04-04-2012, 04:42 AM

Quote:

Originally Posted by SarahGurung

Well online dns test shows that the following :

.....
Actually ns0 is used for zone transfer only,doe real dns purpose other dns server(ns1 an dns2) is used ...

....

I'm sorry I didn't quite well understand your question.

- what online dns test ?
can you provide a link ?

- ns0 is used for zone transfer ...?
Transferring zones from where to ?

If it's somehow only a rsync set on this server to transfer (only my guess what it is), then it's not configured for DNS and that means that the server which handles your domain should have take care of that

good luck

SarahGurung · 04-04-2012, 04:48 AM

No,the bind has been correctly configured and it's a live server..it has centos 5.8 running..We are ISP.

well i checked for our domain at http://dnscheck.pingdom.com and there it showe the errors as said above. And what i meant previously was ns0 is not used for resolving names,dat is done by slave servers.

So is it ok even if udp and tcp is blocke/filtered as ns0 is not used for resolving names.
And i wanted to know what that error meant.

lithos · 04-04-2012, 05:18 AM

Quote:

Originally Posted by SarahGurung

No,the bind has been correctly configured and it's a live server..it has centos 5.8 running..We are ISP.

well i checked for our domain at http://dnscheck.pingdom.com and there it showe the errors as said above. And what i meant previously was ns0 is not used for resolving names,dat is done by slave servers.

So is it ok even if udp and tcp is blocke/filtered as ns0 is not used for resolving names.
And i wanted to know what that error meant.

well, that explains it all.

If it's not name resolver then it shouldn't response to DNS queries (resolving).

The error is probably because of the settings for your domain at the master DNS server,
which may have configured
ns0.domainname.com
as a primary DNS for the domain.

As I can assume you have ns1 as primary domain server so it should be changed on TOP LEVEL domain registrar to point to ns1... not ns0.

And domain querying is actually running through UDP port 53 and not TCP (rarely I've seen it, I can't remember which it was).

good luck

SarahGurung · 04-04-2012, 05:29 AM

No..nso is the master...

Wheneva we create zones,we create it here first which then is copied to slaves as well as slave zone(automatically).

lithos · 04-04-2012, 06:52 AM

Quote:

Originally Posted by SarahGurung

.....

Wheneva ....

Please use ENGLISH language here at LQ forum....

whatewa, I can presume it is a master DNS server so you should then configure it to respond to DNS queries,
or if you do not want to have it respond to queries (for whichever reason that you have), then leave it to slaves, as you have it now (but you could have trouble resolving your domain - eg. example.com).
You can check it here if your domain is configured properly.

SarahGurung · 04-04-2012, 07:02 AM

oh ok thanks..that means it's ok even if the master doesn't reply to the queries if slave is doing that..

And ya i checked it in the link u provided and everything looked good except the dns part where it said that the ns0 isn't replying to the queries..so i suppose that's good hopefully..

And ya i was using English language only,sorry about those shortcuts as I'm used to it..haha...will try to avoid it from next time..