What happened:
Send query to coredns and failed due to "SERVFAIL"
What you expected to happen:
successful query
How to reproduce it (as minimally and precisely as possible):
'nslookup us.data.logs.insight.rapid7.com'
Anything else we need to know?:
captured the logs/tcpdump for investigation and found below behavior
coredns recieved request from client and it sent to upstream successfully. After got response from upstream, it didn't return the result to client but sent query to check the NS server and the previous dns query again and again which was over 5s

Environment:

• the version of CoreDNS: 1.6.6 in AKS
• Corefile: N/A
• logs, if applicable:

1. client tcpdump
   
2. coredns tcpdump
   
3. logs
   [INFO] 10.244.2.137:39886 - 31370 "A IN us.data.logs.insight.rapid7.com. udp 49 false 512" NOERROR - 0 5.000450902s
   [ERROR] plugin/errors: 2 us.data.logs.insight.rapid7.com. A: dns: overflowing header size

• OS (e.g: cat /etc/os-release): ubuntu 16.04
• Others: