avahi: Ping Can’t Resolve Hostname, but nslookup Can – Linux DNS Issue

ping tells me that it can't resolve some hostname ("ping: unknown host domain.company.local") in a URL but when I use host or nslookup on the same computer on the command line, the resolutions works fine (i.e. it's fast and reliable).

What could be causing this?

More testing: Firefox, wget and ping have the same problem. Pinging the IP address works.

OS: Linux (Ubuntu 13.04)

EDIT My /etc/resolv.conf reads:

nameserver 127.0.1.1
search domain.company.local

netstat reports:

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN      -               

so something is running on this port (nslookup also reports it uses 127.0.1.1 as DNS server).

There is no /etc/*inetd.conf, so I'm not sure which application serves this port.

It seems that dnsmasq is used:

/usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces
   --pid-file=/var/run/NetworkManager/dnsmasq.pid --listen-address=127.0.1.1
   --conf-file=/var/run/NetworkManager/dnsmasq.conf --cache-size=0 --proxy-dnssec
   --enable-dbus=org.freedesktop.NetworkManager.dnsmasq
   --conf-dir=/etc/NetworkManager/dnsmasq.d

All the config files and folders are empty. Since nslookup says it uses 127.0.1.1#53 my guess is that dnsmasq works even without a configuration. But how does it know which parent DNS to query?

EDIT2 Disabling dnsmasq as suggested by harrymc didn't help. So I ran strace ping which gave me this odd output (just the interesting parts):

open("/etc/host.conf", O_RDONLY|O_CLOEXEC) = 4
read(4, "127.0.0.1\tlocalhost\n#127.0.1.1\ta"..., 4096) = 613
...
open("/lib/libnss_mdns4_minimal.so.2", O_RDONLY|O_CLOEXEC) = 4
read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\f\0\0\0\0\0\0"..., 832) = 832
...
mmap(NULL, 2105560, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x7f7829b00000
...
socket(PF_FILE, SOCK_STREAM, 0)         = 4
fcntl(4, F_GETFD)                       = 0
fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
connect(4, {sa_family=AF_FILE, path="/var/run/avahi-daemon/socket"}, 110) = 0
fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR)
fstat(4, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f782a4f8000
lseek(4, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
write(4, "RESOLVE-HOSTNAME-IPV4 domain.com"..., 44) = 44
read(4, "-15 Timeout reached\n", 4096)  = 20

So ping looks in /etc/hosts which makes sense. Then it loads and mmap()s /lib/libnss_mdns4_minimal.so.2 which makes sense as well.

But then it talks to avahi!?

Which led me to this forum post: ping doesn't make a dns request.

My /etc/nsswitch.conf also contains this line:

hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4

If I ping a working address, I see that the process also loads /lib/libnss_mdns4_minimal.so.2 but then, it does a DNS query via port 53.

So my guess is now that /lib/libnss_mdns4_minimal.so.2 is somehow noticing that the IP address ends with .local and not with .com and then the [NOTFOUND=return] is triggered.

How do I fix this?