[Dnsmasq-discuss] Redundant setup with Dnsmasq

[Jan Seiffert]

2011/12/22 Markus Schöpflin <markus.schoepflin at comsoft.aero>:
> Thank you for your idea. This really seems OK for our needs. If I understand
> things correctly, I would have to do that on all four LANs the current Dnsmasq
> is serving. Just one small additional question:
>
> Am 22.12.2011 15:13, schrieb Michael Rack:
>
>> Very easy.
>>
>> You need at least one virtual ip-address for your DNS- and DHCP-Server.
>>
>> So lets say you have a Class-C Network 10.0.0.0/24
>>
>>       * Primary DNS / DHCP    10.0.0.251
>>       * Secondary DNS / DHCP  10.0.0.252
>>
>> Now, you add a virtual IP to your primary DNS - lets say
>>
>>       * Virtual-IP            10.0.0.250
>>
>>   From Secondary you create a Bash-Script that do the following:
>>
>>       * Check the Server-Status by ping the virtual ip-address
>>       * when the ping has failed:
>>          * add the virtual ip-address to your network-configuration
>
> Wouldn't it make sense to send an unsolicited ARP packet to update the ARP
> caches of neighbours after the IP address has moved?
>

Yes.
I was about to write the same tip.
Sometimes ARP-Tables can have a quite long timeout, so the "failover"
would be stuck.
Maybe something along the lines of
arping -c 1 -A -s 10.0.0.250 $BROADCAST_ADDR

[snip]
>
> Thank you,
> Markus
>

Greetings
Jan

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