search domain in resolv.conf is not appending to hosts when doing ping or other network communciation

debian dns search resolv.conf

14,436

Ok - so this was pretty oversighted of me but here was the issue. I had the domain1.local listed under the domain parameter in the /etc/resolv.conf

### Standard Search domains:
search domain1.local domain2.local
domain domain1.local # removed this line

After I ran the debug on nslookup and noticed that it was trying to append domain1.local for the nslookup I removed this and clearly it fixed the issue.

user@host:~$ nslookup hosty
Server:     192.16.1.110
Address:    192.16.1.110#53

Name:   hosty.domain2.local
Address: 192.16.48.20

Pretty stupid of me but just in case someone else makes the same mistake maybe this could help them.

14,436

Author by

Alex Tomko

Updated on September 18, 2022

Comments

Alex Tomko over 1 year
I am trying to find out why multiple search domains do not work with Debian 8.8.0. If you add the search domains in /etc/resolv.conf it will only work with one of them & in this case domain1.local works but domain2.local will not.

If you manually append the FQDN it works fine. This is for any and all CLI based tools: nslookup, ping, iperf, nmap, curl, wget ect. I have seen this before where Debian does not work with .local domains - and you have to remove avahi which I have already done to get the first .local domain working: domain1.local.

I have had multiple .local & other domain's working but with this version of Debian 8.8.x it is not working.
```
user@host:~$ uname -a
Linux host 3.16.0-4-amd64 #1 SMP Debian 3.16.43-2+deb8u2 (2017-06-26)     x86_64 GNU/Linux


user@host:~$ cat /etc/resolv.conf

nameserver 192.16.1.110
### Standard Search domains:
search domain1.local domain2.local domain3.local domain4.local
```
search domain - domain1 automatically appends the domain1.local and works for nslookup, ping ect.
```
user@host:~$ ping host1
PING host1.domain1.local (192.16.1.110) 56(84) bytes of data.
64 bytes from host1.domain1.local (192.16.1.110): icmp_seq=1 ttl=118    time=63.6 ms

user@host:~$ nslookup host1
Server:     192.16.1.110
Address:    192.16.1.110#53

Name:   host1.domain1.local
Address: 192.16.1.110
```
domain2 will not automatically be appended to the host (hosty) in this example. It will not find hosty with an nslookup from the dns server in /etc/resolv.fon (although it does exist). However - if you append the FQDN and run an nslookup, ping, curl,nmap,wget or any other cli based ip communication it works.
```
user@host:~$ nslookup hosty
;; Got SERVFAIL reply from 192.16.1.110, trying next server
;; Got SERVFAIL reply from 192.16.1.111, trying next server
Server:     192.16.1.110
Address:    192.16.1.110#53

** server can't find hosty: SERVFAIL

user@host:~$ ping hosty
ping: unknown host hosty
```
If we append domain2.local on the end of the host it can ping, nslookup, or other.

ping,nslookup & curl working with fqdn
```
user@host:~$ ping hosty.domain2.local
PING hosty.domain2.local (192.16.48.20) 56(84) bytes of data.
64 bytes from hosty.domain2.local (192.16.48.20): icmp_seq=1 ttl=119 time=63.6 ms

nslookup with fqdn:

user@host:~$ nslookup hosty.domain2.local
Server:     192.16.1.110
Address:    192.16.1.110#53

Name:   hosty.domain2.local
Address: 192.16.48.20

user@host:~$ curl hosty.domain2.local
curl: (7) Failed to connect to hosty.domain2.local port 80: Connection refused
```
It is worth mentioning that I have this identical configuration on a Ubuntu 16.04 workstation working with around 7 search domains.

The new Debian 8.8.x servers have the issue with working with more than 1 search domain. I must be missing some simple additional configuration that is required for Debian that is slightly different than Ubuntu.
- Barmar almost 7 years
  
  Try using nslookup -debug to see the exact queries that are being tried. The key to the problem may be that you're getting SERVFAIL errors rather than NXDOMAIN. Also, dig is generally a better debugging tool than nslookup.
- Barmar almost 7 years
  
  Of course it's trying to append domain1.local. It tries each domain in order: first it appends domain1.local, if that can't be found it appends domain2.local, and so on until it gets success. The server should return an NXDOMAIN response for hosty.domain1.local, then it will try the next domain.
Alex Tomko almost 7 years

I attempted this configuration however I like to rely on the /etc/resolv.conf for DNS. It does not work either with dns-nameserver in the ethx's inside of /etc/network/interfaces either. This server has anywhere from 10-15 interfaces doing alot of routing for automation ect for internal networks. The servers do not rely on resolvconf and must be staticly managed.
Alex Tomko almost 7 years

I also always remove resolvconf, avahi, network-manager from any servers.
Alex Tomko almost 7 years

# eth4 iface eth4 inet static address 172.19.51.252 netmask 255.255.255.0 dns-nameservers 192.16.48.20 dns-search domain2.local # eg - same failed results.