Question

4

Can resolve hostname via dns using `host` but can't ping/ssh/ntp

rated 0 times [ 4] [ 0] / answers: 1 / hits: 33566 / 2 Years ago, wed, january 26, 2022, 1:26:06

I'm setting up a local network and have configured a DNS server. I can resolve hostnames by querying the DNS server, but no programs can look them up.

I uninstalled libnss-mdns and removed avahi-daemon and even rebooted afterwards.

Here are some examples:

root@cloud2:~# host ns.example.com

ns.example.com has address 10.10.10.100

root@cloud2:~# ping ns.example.com

ping: unknown host ns.example.com



root@cloud2:~# grep hosts /etc/nsswitch.conf 

hosts:          files dns

my ntp server is configured for ns.example.com, but all I get is nxdomain on ntpq

any ideas?

EDIT:

This also applies to external DNS entries. I have my router both as a DNS forwarder on the custom DNS server and as an entry in resolvconf.

E.G.

root@cloud2:~# host google.com | head

google.com has address 74.125.225.65

google.com has address 74.125.225.66

google.com has address 74.125.225.67

google.com has address 74.125.225.68

google.com has address 74.125.225.69

google.com has address 74.125.225.70

google.com has address 74.125.225.71

google.com has address 74.125.225.72

google.com has address 74.125.225.73

google.com has address 74.125.225.78

root@cloud2:~# traceroute google.com

google.com: Temporary failure in name resolution

Cannot handle "host" cmdline arg `google.com' on position 1 (argc 1)

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answered 2 Years ago beateyra · Accepted Answer

This was on Ubuntu server 12.04 LTS and Ubuntu 12.04 LTS

Thanks all for the help. Turns out to be a result of a difference in the way host and the glibc resolver read /etc/resolv.conf.

I was managing resolv.conf with a puppet module that edited the appropriate files in /etc/resolvconf/resolv.conf.d/.

Said puppet module resulted in an /etc/resolv.conf that looked like this:

 nameserver 10.10.10.100

 nameserver 192.168.3.100

 nameserver 10.10.10.1



 search example.com

with a space at the beginning of each line. After removing these spaces, I was able to resolve with both ping and manual lookups (host/nslookup/etc...)

I could've sworn that I've had those spaces on other OSes with no issues, but I just tried on a SL6.3 box and it caused the same behavior.

Thanks for your help and sorry for the trouble!