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I have two bind9 servers that are not setup with duplicate settings and know nothing about each other. Our CPU usage is sitting around 7% - 10%: mostly bind, which I believe is perfectly in range for our load. However, CPU usage is slowly growing increasing every week and I estimate that I have at least 4-5 months before this becomes an issue. Just want a clarification - would a Master/Slave setup reduce CPU on the slave?

We are using the service as a forwarding server allowing IP ACL based recursive look-ups. The only fail over is the fact that our DNS users input both DNS addresses in their setup. It doesn't do dynamic updates, we have a small list of DNS records that get changed maybe once or twice a quarter.

Kladskull
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  • What problem are you trying to solve? – Nathan C Dec 02 '14 at 15:25
  • We have two servers that are not setup in a master/slave setup, our CPU usage is sitting around 7% - 10% (mostly bind) and getting higher every week. I estimate that I have at least 4-5 months before this becomes an issue, but I was thinking that a Master/Slave setup could reduce CPU on the slave system at least. – Kladskull Dec 02 '14 at 15:29
  • Any input on the down votes would be helpful to me, just looking for guidance. – Kladskull Dec 02 '14 at 15:30
  • It would be helpful to update your question with the problems you're having so appropriate solutions can be given. – Nathan C Dec 02 '14 at 15:31
  • I didn't vote down (yet), but there are some basic questions you have not answered. What do you use the DNS for? Does it do dynamic updates? Are you doing a failover? For the most part, there is no reason not to set up a DNS slave for static DNS serving operations. – Andrew Domaszek Dec 02 '14 at 15:31
  • I've updated my question with some of the asked information, appreciate the patience. – Kladskull Dec 02 '14 at 15:38

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DNS operates best in a Master/Slave scenario. Consider this: you have two nameservers, ns1 and ns2. To help balance the load, you have two NS records in your domain record for both ns1 and ns2. By the very nature of DNS, clients will query the nameservers in random order because nameserver lookups are returned in a random order. See this answer for helpful information.

If you're running into performance problems even with this current setup, add another nameserver to help support the load or give your existing servers additional resources.

Community
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Nathan C
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  • Thanks Nathan, this was very helpful. The link you posted is pretty much what I think I was looking for, as well as mentioning that I can use multiple records for NS, which I think I may have read, but didn't hit the note. – Kladskull Dec 02 '14 at 15:50