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This is interesting! Do you have some material on load testing the DNS servers and seeing their breaking point? I've heard as much from other people but never e
by aprdm 7y ago
This is interesting! Do you have some material on load testing the DNS servers and seeing their breaking point? I've heard as much from other people but never experienced it in practice even using Consul with 0 TTL everywhere.
Perhaps the network infrastructure team always scaled it correctly behind the scenes but they never once complained about the amount of DNS queries.
- takeda 7y agoDNS is fairly lightweight and if you have one local on premises, it might be less noticeable, especially if latency is not critical (in previous places I worked that was the setup, we still had a local cache on every host and I would encourage doing that, it increases resiliency). If latency is critical, not having a cache adds extra round trip on every connection initiated. If you have hosts on public cloud and use DNS server that is also shared with others the latency typically might be bigger and on high number of requests you might also start seeing SERVFAIL on large number of requests. I can't find the forum post anymore, but people who had applications that were opening large number of connections (bad design of the app imo, but still) had huge performance degradation when they moved from c4 to c5 instances. It turned out that this was because of the move from Xen to Nitro (based on KVM). Side effect of using Xen was that the VM Host was actually caching DNS requests by itself, from which all guests benefited. In the KVM, all DNS requests were going directly to the DNS server.