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2 Apache web servers with identical vhosts to serve a few hundred clients. RHEL 6 on all boxes. What are the pros and cons to having a load balancer with a VIP, and pointing all of the DNS A records to the VIP vs having no load balancer in front and just using 2 A records for each site, one with server A IP, and the other with server B.

usedTobeaMember
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  • possible duplicate of [Is Round-Robin DNS "good enough" for load balancing static content?](http://serverfault.com/questions/101053/is-round-robin-dns-good-enough-for-load-balancing-static-content) – Ladadadada May 04 '14 at 20:12

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Pro for dedicated load balancer:
It actually can balance the load (depends on the software of course).
You can disable a backend node without anyone noticing it.
If a node crashes only the current connection dies (if at all) and the next request from the same client goes to a different node (vs. the client caches DNS and hits it again and again).

Pro for DNS round robin?
I don't know. It's cheap I guess.

faker
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@faker has a good answer. i would comment to that, but my rep does not allow. a couple of additional pros for each:

load balancer

  • can reliably scale (dns cache can delay RR scaling)
  • in most cases, you can have a heterogenous cluster with machines of different capabilities - with RR, you are only as strong as your weakest link

RR

  • likely marginally faster, since there's less routing
  • one less point of failure (less true if you are using a managed lb like AWS ELB)
J. Paulding
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Pros of RR dns:

  • cheap
  • easy

Cons of RR dns:

  • in case of host failure, you loose all the traffic while restoring it (or at least the time of dns propagation for a new ip)
R.Sicart
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