[SOLVED] Bind9 DNS "partially" working

banderas20 · 11-27-2023, 07:46 AM

Hi,

I have an strange issue with bind9 which I can't solve.

I have defined my own and local domain, domain.local.
In the forward resolution file I have the following entries:

Code:

domain.local. IN A 172.17.70.1
www IN CNAME domain.local.

nslookup resolves domain.local and www.domain.local as 172.17.70.1 (as expected).

However, http or ping commands only reply to www.domain.local, and not to domain.local.

¿What am I doing wrong?

Thanks!

bathory · 11-27-2023, 11:25 AM

Quote:

Originally Posted by banderas20

Hi,

I have an strange issue with bind9 which I can't solve.

I have defined my own and local domain, domain.local.
In the forward resolution file I have the following entries:

Code:

domain.local. IN A 172.17.70.1
www IN CNAME domain.local.

nslookup resolves domain.local and www.domain.local as 172.17.70.1 (as expected).

However, http or ping commands only reply to www.domain.com, and not to domain.local.

¿What am I doing wrong?

Thanks!

I guess you mean www.domain.local and not www.domain.com above

Anyway, nslookup uses a nameserver in order to resolve a domain/hostname

Other protocols like ping, http etc are looking in the hosts file (/etc/hosts) before asking a nameserver.
If they find an entry about that hostname they are using that in order to connect.

So check /etc/hosts and remove any entry about (www.)domain.local
Then you need to make sure that you nameserver is used as a resolver by your box. You should read your distro's documentation about /etc/resolv.conf, Network Manager or other means your distro is using to define a resolver.

Regards

banderas20 · 11-27-2023, 12:14 PM

Quote:

Originally Posted by bathory

I guess you mean www.domain.local and not www.domain.com above

Anyway, nslookup uses a nameserver in order to resolve a domain/hostname

Other protocols like ping, http etc are looking in the hosts file (/etc/hosts) before asking a nameserver.
If they find an entry about that hostname they are using that in order to connect.

So check /etc/hosts and remove any entry about (www.)domain.local
Then you need to make sure that you nameserver is used as a resolver by your box. You should read your distro's documentation about /etc/resolv.conf, Network Manager or other means your distro is using to define a resolver.

Regards

Yes. I meant www.domain.local. It was a typo.

I didn't know about the different checks done by ping and nslookup. Thanks for the guidance. I'll take a closer look at my config and post the results.

BTW, I have 2 different NICs. Each one with a different DNS attached to it. Can this be the issue?

Thank you very much!

bathory · 11-27-2023, 12:47 PM

Quote:

I didn't know about the different checks done by ping and nslookup. Thanks for the guidance. I'll take a closer look at my config and post the results.

BTW, I have 2 different NICs. Each one with a different DNS attached to it. Can this be the issue?

No I don't think this has something to do with your issue, but you can try ping and dig with your hostname in order to see how it's resolved by the 2 utilities:

Code:

dig www.domain.local
ping www.domain.local

banderas20 · 11-27-2023, 05:13 PM

Quote:

Originally Posted by bathory

No I don't think this has something to do with your issue, but you can try ping and dig with your hostname in order to see how it's resolved by the 2 utilities:

Code:

dig www.domain.local
ping www.domain.local

dig www.domain.local

;; ANSWER SECTION:
www.domain.local. 604800 IN CNAME domain.local.
domain.local. 604800 IN A 172.17.70.1

dig domain.local

;; ANSWER SECTION:
domain.local. 604800 IN A 172.17.70.1

ping www.domain.local -> sucess
ping domain.local -> fail!

bathory · 11-28-2023, 01:09 AM

Quote:

ping www.domain.local -> sucess
ping domain.local -> fail!

That says nothing about the name resolution. You should see the IP address that ping uses, e.g:

Code:

ping google.com
PING google.com (216.58.212.46) 56(84) bytes of data.

ping www.google.com
PING www.google.com (142.251.140.68) 56(84) bytes of data.

banderas20 · 11-28-2023, 05:32 AM

Right. Here it goes:

Code:

ping www.domain.local

PING domain.local (172.17.70.1) 56(84) bytes of data.
64 bytes from MASTER (172.17.70.1): icmp_seq=1 ttl=64 time=0.055 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=2 ttl=64 time=0.111 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=3 ttl=64 time=0.079 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=4 ttl=64 time=0.079 ms

ping domain.local

ping: domain.local: Name or service not known

bathory · 11-28-2023, 10:59 AM

Quote:

ping www.domain.local

PING domain.local (172.17.70.1) 56(84) bytes of data.
64 bytes from MASTER (172.17.70.1): icmp_seq=1 ttl=64 time=0.055 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=2 ttl=64 time=0.111 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=3 ttl=64 time=0.079 ms
64 bytes from MASTER (172.17.70.1): icmp_seq=4 ttl=64 time=0.079 ms

ping domain.local

ping: domain.local: Name or service not known

You didn't say your distro, so we cannot know if you're using Network Manager or other network tool.

What's in /etc/hosts and /etc/resolv.conf (or whatever file your resolver is using!)

banderas20 · 11-29-2023, 10:25 AM

Mi box is Ubuntu 20.04.6 LTS.

Code:

cat /etc/hosts
127.0.0.1	localhost
127.0.1.1	MASTER
172.17.70.1	MASTER

Code:

cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 172.17.70.1
search domain.local

Hope this helps.

Thanks!

bathory · 11-29-2023, 12:01 PM

Quote:

Originally Posted by banderas20

Mi box is Ubuntu 20.04.6 LTS.

Code:

cat /etc/hosts
127.0.0.1	localhost
127.0.1.1	MASTER
172.17.70.1	MASTER

Code:

cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 172.17.70.1
search domain.local

Hope this helps.

Thanks!

AFAIK ubuntu uses avahi with a .local domain, so maybe that's the reason of this mess in dns name resolution!
I don't use ubuntu, but I've this post why using a .local domain is a bad idea.

Also re. your network config you should put your nameserver first and google second in /etc/resolv.conf, so your box uses the local dns resolver to resolve a fake domain (like .local or whatever) that your nameserver is authoritative for.

banderas20 · 12-01-2023, 05:35 AM

Quote:

Originally Posted by bathory

AFAIK ubuntu uses avahi with a .local domain, so maybe that's the reason of this mess in dns name resolution!
I don't use ubuntu, but I've this post why using a .local domain is a bad idea.

Also re. your network config you should put your nameserver first and google second in /etc/resolv.conf, so your box uses the local dns resolver to resolve a fake domain (like .local or whatever) that your nameserver is authoritative for.

Indeed commenting out the 8.8.8.8 server solved some issues.
Now I'll try to change my domain to another different from .local.

Thanks for the links. I'll post the results.

MadeInGermany · 12-01-2023, 07:55 AM

dig and nslookup do a direct dns lookup.

Generic host lookups are done according to the hosts: line in /etc/nsswitch.conf
"files" means /etc/hosts.
"myhostname" is explained in

Code:

man nss-myhostname

Testing just the generic host lookup

Code:

getent hosts domain.local

banderas20 · 12-03-2023, 04:59 PM

Quote:

Originally Posted by bathory

AFAIK ubuntu uses avahi with a .local domain, so maybe that's the reason of this mess in dns name resolution!
I don't use ubuntu, but I've this post why using a .local domain is a bad idea.

Also re. your network config you should put your nameserver first and google second in /etc/resolv.conf, so your box uses the local dns resolver to resolve a fake domain (like .local or whatever) that your nameserver is authoritative for.

Hi!

I put my nameserver fix and that seemed to solve some issues. Also, after changing .local to .here domain, everything seemed to work as expected.

Quote:

Originally Posted by MadeInGermany

Generic host lookups are done according to the hosts: line in /etc/nsswitch.conf
"files" means /etc/hosts.

I don't have

Code:

nss-myhostname

command installed in by box.

I don't know the purpose of

Code:

getent hosts domain.local

either. ¿Can you shed some light?

Thanks a lot to both of you!

MadeInGermany · 12-04-2023, 02:31 AM

I suggested

Code:

man nss-myhostname

and you'll see it is a binary plugin for the hostname resolution, corresponding to a "myhostname" in /etc/nsswitch.conf
The man page is just a description what it does.
Likewise, a description of /etc/nsswitch.conf is in

Code:

man nsswitch.conf

Code:

getent hosts myhostname
getent hosts myipaddress

shows what the hostname resolution yields.
Knowing how it works is the first step in finding a solution.

banderas20 · 12-06-2023, 03:38 PM

Quote:

Originally Posted by MadeInGermany

I suggested

Code:

man nss-myhostname

and you'll see it is a binary plugin for the hostname resolution, corresponding to a "myhostname" in /etc/nsswitch.conf
The man page is just a description what it does.
Likewise, a description of /etc/nsswitch.conf is in

Code:

man nsswitch.conf

Code:

getent hosts myhostname
getent hosts myipaddress

shows what the hostname resolution yields.
Knowing how it works is the first step in finding a solution.

Thanks!

Closing thread, as it's already solved!