Number of A-Records in Load Balancing with Multiple A-Records

Stefan Puiu stefan.puiu at
Mon Jun 12 06:59:49 UTC 2006

One thing you'll have to think about - with that amount of nameservers
to return, any non-EDNS0 query for your domain will have to fall back
to TCP, thus making resolution slower. I don't know how many resolver
libraries generate EDNS0 queries by default.

You can check out as an example, or there was even
another one on this list, somebody who had 407 (!) nameservers (check
out, and the packet size on return would exceed 4K, so even
EDNS0 couldn't do anything.

I guess this could qualify as 'side effect'.


On 6/11/06, mail at <mail at> wrote:

> Is there someone who has some operating experience with environments that have
> about 30 or up to 50 A-Records for an FQDN?

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