Docker nslookup works but not wget

Question

I have the following setup:

• a dns server with an A entry for myhost1.mycompany -> 10.10.10.1
• a server myhost2 (debian11) with docker daemon (20.10.5) installed and a runing container mycontainer1 on it
• on myhost2, the private dns server is configured in /etc/resolv.conf with search mycompany

On myhost2:

• nslookup myhost1 -> 10.10.10.1
• ping myhost1 -> works
• wget myhost1 -> wokrs
• wget google.com -> works

On mycontainer1:

• nslookup myhost1 -> 10.10.10.1
• ping myhost1 -> bad address
• wget myhost1 -> bad address
• wget google.com -> works
• cat /etc/resolv.conf -> same output as cat /etc/resolv.conf on myhost2

So this is not (I guess) a DNS issue as nslookup queries work fine from the container, but I can't figure out why other application (like ping or wget) can't get the resolved ip..

Thanks for sharing your ideas !

Answer 1

That behavior may be caused by the option ndots:0 in /etc/resolv.conf which prevents ping from adding your default local domain.

In this situation, ping myhost1.mydomain.lan should work, where ping myhost1 should not (and the same with wget).

So I suggest you can try to change it to ndots:5.

For example :

nameserver 127.0.0.11
options ndots:5