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How can DNS BIND capacity can be calculated i.e. How many queries DNS can handle per second? I am facing an issue where DNS is not responding to some of the queries and my technical support is saying that is cuz DNS capacity is being exceeded. He is quoting the figure of maximum 10,000 queries/second that DNS can handle but i am not sure how this figure is being calculated.

I am using BIND 9.4.3 and my system is 16 CPU core Intel 2.13GHz. CPU usage is around 6% of each processor.

Thanks

zohaib manzoor ahmed
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This is off-topic for here, but truly the answer can only be found by benchmarking on your specific architecture. It also makes a massive difference whether you're talking about recursive or authoritative DNS service. For former is generally slower because your server has to reach out to the internet to find the answers it needs.

The version of BIND you are running is very old, BTW. Newer versions have much improved multithreading support, although that wasn't enabled by default until 9.10. More at https://kb.isc.org/article/AA-00629/0/Performance%3A-Multi-threaded-I-O.html

See also my recent blog article at https://www.isc.org/blogs/benchmarking-dns/

Alnitak
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  • Thanks a lot for your response. We are using recursive DNS server and send requests to a public DNS server for authoritative answer. – zohaib manzoor ahmed Jul 18 '15 at 12:03
  • Alnitak makes some very good points. It is very important to specify how much of your traffic is locally resolved and how much you have to fetch from external servers. Zone structure also has some importance, as badly built zones can cause traffic to fall back to TCP a lot more often, having a huge impact on each transaction. – Rick Buford Jul 19 '15 at 02:52