Re: Recommended DNS server for a medium 20-30k users isp

[Tom Beecher via NANOG <nanog () lists nanog org>]

> We have used powerdns and unbound but sometimes find the caching times a
> bit on upper side.


By default, unbound caches an entry for the duration of the TTL received
from the authoritative server. You can modify this .
- cache-min-ttl  : if TTL less than this, cache it at least this long
- cache-max-ttl : if TTL is more than this, only cache it this long

There are many other config options in unbound that allow you to tune cache
behaviors to your desired use case. A cursory look at PowerDNS docs show
that has similar options.

I'd suggest working with the software you already have to see if it can be
configured to meet your requirements first. Likely to be less effort.


On Thu, Aug 7, 2025 at 8:45 PM DurgaPrasad - DatasoftComnet via NANOG <
nanog () lists nanog org> wrote:

> Hello all,
> Do you have any recommendations for recursive DNS servers for a medium
> sized (20-30k users) ISP.
> We have used powerdns and unbound but sometimes find the caching times a
> bit on upper side. Any suggestions between these two or anything new?
> Also need points on how much we tune the settings
> pros and cons if any.
>
> Thank you /DP
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