Round robin load distribution among servers does not work properly

[Mallappa Pallakke]

Hi,

    I was trying to do load balancing of client request among
configured servers using internal DNS server, I get proper load
balaning (DNS response with top most IP address going with proper
round robin fashio) for odd number of IP addresses. But it does not
give same bevior for even number of IP addresses.

For example:

  If I have configured x.y.z.1, x.y.z.2, x.y.z.3, I get following
combinations in dig response:

  x.y.z.1
  x.y.z.2
  x.y.z.3

  x.y.z.2
  x.y.z.3
  x.y.z.1

  x.y.z.3
  x.y.z.1
  x.y.z.2

And this repeats, giving round robin distribution.

However, if I add one more IP address to the zone list (x.y.z.4), I
get only following combinations:

x.y.z.1
x.y.z.2
x.y.z.3
x.y.z.4

and

x.y.z.3
x.y.z.4
x.y.z.1
x.y.z.2

It gets repeated. I will never get x.y.z.2 and x.y.z.4 as top entries
in this response.

Can anybody tell me why this limitation and is there any sollution to
resove this problem?

Thanks in advance.

Mallappa