I have a strange situation. Pinging by ip works fine, but by host name fails. My observations:
nslookup -type=ns google.com ;; connection timed out; no servers could be reached
In one window I called:
ping google.com ping: unknown host google.com
and in the other window I had this:
sudo tcpdump -n -i eno1 |grep -A5 172.27.1.100.53 # this is my dns server 11:06:57.336938 IP 172.27.6.77.48852 > 172.27.1.100.53: 61526+ A? google.com. (28) 11:06:57.337151 IP 172.27.1.100.53 > 172.27.6.77.48852: 61526 1/0/0 A 22.214.171.124 (44) 11:06:57.337170 IP 172.27.6.77 > 172.27.1.100: ICMP 172.27.6.77 udp port 48852 unreachable, length 80
As you can see in the tcpdump there was a response from DNS server and google.com was properly resolved: 126.96.36.199.
What's going on here? Can I somehow debug it more?
I know that when I restart my network it would work fine, because it happened few times earlier. This is only workaround and it doesn't resolve my isssue.
I am using ubuntu 16.04 (desktop).