Implement DNS round-robin in the RRSets on response to client
There are still some services that rely on DNS Round-Robin of RRs in the RRSets returned to such client. Thus there should be an option to enable round-robin of RRSets.
This could be implemented in number of ways:
- persistent deterministic round-robin, e.g. keep the current HEAD in the cache backend; the advantage here is that the round-robin ordering is kept across all instances using shared cache, but the disadvantage is writing into the cache at every read access
- shuffle the output for the client, possible options: random, pseudo-random, time-based (e.g. pick
timestamp%<n>
order)?
In any case this might have an impact on the performance because it usually applies to the records that are already in the cache.