Choosing A records based on hosts' load?

Matus UHLAR - fantomas uhlar at
Mon Jan 18 09:20:32 UTC 2021

On 18.01.21 09:49, Marek Kozlowski wrote:
>I believe that such a solution (read to install) should exist. 
>Unfortunately I don't know the magic keywords to find it:
>I have a group of hosts with different IPs offering the same services. 
>I'm able to install some agents on them for monitoring their 
>network/cpu/number of users/whatever utilization. I'm wondering if 
>there is an option for BIND9 to obtain those load parameters on a 
>regular basis (let's say: every 10 minutes) and when queried for the A 
>record return ONLY one IP address - the one of the server with the 
>lowest utilization?

and whenever one of servers hits the lowest utilization, all connections get
directed to it, which will result in highest utilization.

>It can be implemented on those servers but in the solution I'm asking 
>about the key point is that the BIND server takes the decision.

This is not problem for BIND nor for DNS. 
Due to DNS caching it won't work properly and if you shorten the TTLs, at
first DNS issue it will fail globally.

Install some load balancers in front of those servers.

Matus UHLAR - fantomas, uhlar at ;
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