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Verifying that DNS forwarders in bind where actually being called

I was setting up bind and wanted to verify that DNS forwarding was working the way I wanted it to

I found tcpdump essential, really helpful

The following was a snippet from http://support.citrix.com/article/CTX124727

 A packet capture on the BIND server shows the query being forwarded to the Global Forwarders defined in the zone configuration file: 
rosa pri # tcpdump -n udp port 53 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes 22:36:39.530000 IP 10.12.17.30.1215 > 10.12.17.4.53: 365+ A? www.citrix.com. (32) 22:36:39.530000 IP 10.12.17.4.40722 > 10.9.3.22.53: 57464+% [1au] A? www.citrix.com. (43) 22:36:39.530000 IP 10.9.3.22.53 > 10.12.17.4.40722: 57464* 1/0/1 A 66.165.176.15 (59) 22:36:39.530000 IP 10.12.17.4.53 > 10.12.17.30.1215: 365 1/0/0 A 66.165.176.15 (48)

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