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Does anyone know how to measure the performance of forwarders that are configured on a BIND DNS (may be in terms of RTT, SRTT)?

This will help to know which forwarders are working optimally, I tend to script this so as to get a trend over a particular period of time.

Adigun Gbenga
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BIND uses SRTT as a variable to decide which DNS to use, so you can get access to it dumping the cache with the command rndc dumpdb will dump the cache in bind's directory (or the directory specified by the dump-file configuration directive).

In that file named_dump.db you will be able to get the SRTT of each nameserver, just grep the file for srttp and you will find the interesting lines, then filter with the IPs of the forwarders you want to look at.

Pablo Martinez
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  • Many thanks Pablo.... Below is the output from one of the DNS servers: ; 83.1xx.8.2xx [srtt 28209] [flags 00002000] [ttl -16542] ; 83.1xx.8.2xx [srtt 28209] [flags 00002000] [ttl -16542] ; 8.8.8.8 [srtt 0] [flags 00000000] [ttl 224] ....... Any idea about the negative TTL value? Also is srtt 0 for 8.8.8.8 make sense? – Adigun Gbenga Jun 26 '15 at 13:23