and so on to 10,000.
When a DNS request comes in to resolve www.domain.com, the fact that there are 10,000 "A" records in the zone has absolutely no bearing on the size of the response back.
You should only get the domain or subdomain you asked for, plus the full list of DNS authorities for that node. Providing unresquested nodes makes no sense and just burdens with extra overhead.
On the other hand:
www.domain.com. IN A 1.2.3.4
In this case, a DNS request to resolve www.domain.com will result in 200 "A" records for that name. This scenario would be troublesome, as it requires a huge response, as you pointed out in your earlier email.
Yes, here we do have a possibility that makes sense. However this manor of things is handled differently than I think Tucows intends for their DNS service.
Basically one way the above is accomplished without excessive overhead is basically DNS equivelent to dynamic HTML pages. Let me explain --
Your comments suggest a static table definition which allways gets mirrored in the response. However you can insert code that randomly selects say 4 of the possible IPs and just returns those IPs for the request. Next DNS request gets 4 different IPs and so on. You can also look at the requesting IP and possibly infer the region the request was made from and then just return the IP's for the servers in that region.
Lot's of ways to handle extensively redundent servers, but I don't think that's what Tucows had in mind. For that level of service contact someone like:
http://www.UltraDns.com
