Dns Servers

[Bob Harold]

On Fri, Nov 25, 2016 at 8:00 AM, Niall O'Reilly <niall.oreilly at ucd.ie>
wrote:

> On 25 Nov 2016, at 12:17, Marcelo Magno Espindola de Melo wrote:
>
> > How many dns servers can I configure for isc-dhcpd to serve?
>
>   There is no specific limit.
>   Beyond two or three, any additional ones are likely not useful.
>
>   I'ld suggest just using two.
>
>   I understand that some clients (used to?) ignore any DNS servers
>   beyond the first two.
>
>   It's  not unusual for clients to attempt to use the DNS servers
>   always in the same order (as given in the DHCP option 6), so that
>   the second one is only used in case a response is not received
>   from the first within the time-limit.  If you configure 5 DNS
>   servers, and for some reason only the last is working, your
>   customers will notice such delays that they won't appreciate the
>   trouble you took to provide four stages of fallback.
>
>   Best regards,
>   Niall O'Reilly
>
>
There might be other clients that try all the addresses at the same time,
so again two is the best number.
If I recall correctly, three was the limit at one point.  So three would
also be ok.
Beyond that, use anycast (preferred) or a load balancer to put more DNS
servers behind the same 2 or 3 IP's.

-- 
Bob Harold
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