one DNS names to multiple IP Addresses(Round Robin DNS)

Sam Wilson Sam.Wilson at ed.ac.uk
Wed Sep 9 16:47:34 UTC 2009


In article <mailman.450.1252511223.14796.bind-users at lists.isc.org>,
 Balanagaraju Munukutla <9balan at sg.ibm.com> wrote:

> Hi
> 
> Anybody can help to explain the side effect of configuring the DNS name to 
> multiple IP addresses(Round Robin DNS).

If you're planning to use it for load sharing, then the effect is very 
basic - requests get shared equally among the addresses irrespective of 
load on the target system or whether the system is offering the service 
or not.  If one of the target systems goes down then clients which are 
directed to that system will either get rejected or time out, depending 
on the type of failure.  You can mitigate this by using watchdog 
scripts, short TTLs and dynamic DNS updates.

In short it's cheap and cheerful load balancing.  A large commercial 
organisation might not want to rely on it, but depending on the 
application it can work well enough.

Sam



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