DNS Resolver Response: Unknow error response(202)

Products

• ProxySG Software - SGOS
• ISG Proxy

Issue/Introduction

DNS health check on Proxy is showing Failed.

From proxy CLI when test dns command is executed getting following error,

ProxySG> test dns example.com

Sending A query for example.com to 4.2.2.2

Sending A query for example.com to 8.8.8.8

DNS Resolver Response: Unknow error response(202)

Packet capture taken on proxy for DNS traffic in pcap we do not see any packet generated by proxy towards configured DNS server

Cause

For example route for DNS server's gateway IP address is XXX.XXX.XXX.XXX then on proxy ARP resolution will be incomplete for that gateway IP address XXX.XXX.XXX.XXX.

Resolution

Check if route for DNS server is present on proxy or not by running following command

ProxySG> show ip-route-table

If route for DNS servers is present then check the arp-table on proxy by running following command and verify that proper arp is learned on proxy for route for DNS server's gateway IP address is XXX.XXX.XXX.XXX

ProxySG> show arp-table

Once the proper ARP is learned then in packet capture you'll see proxy will start sending DNS query.