nanog mailing list archives
Re: DNS caches that support partitioning ?
From: Andrew Sullivan <asullivan () dyn com>
Date: Fri, 17 Aug 2012 17:12:11 -0400
On Fri, Aug 17, 2012 at 04:32:45PM -0400, valdis.kletnieks () vt edu wrote:
I think John's issue is that he's seeing those other queries *not* benefiting from the caching because they get pushed out by DNSBL queries that will likely not ever be used again. You don't want your cached entry for www.google.com to get pushed out by a lookup for a dialup line somewhere in Africa.
Oh, yes, I see. You're right, I misread it. But the proposed solution still seems wrong to me. If the entry for www.google.com gets invalidated by a new cache candidate that is never going to get used again, the cache is simply too small (or else it doesn't have enough traffic, and you shouldn't have a cache there at all). The cache needs to be big enough that it has a thrashy bit that is getting changed all the time. Those are the records that go into the cache and then die without being queried again. If the problem is that there's some other record in there that might be queried again, but that doesn't get queried often enough to keep it alive, then the additional cost of the recursive lookup is just not that big a deal. Best, A -- Andrew Sullivan Dyn Labs asullivan () dyn com
Current thread:
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?], (continued)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Chris Adams (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Patrick W. Gilmore (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Tony Finch (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Shumon Huque (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Tony Finch (Aug 20)
- Message not available
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Tim Chown (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Nick Hilliard (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Mark Andrews (Aug 20)
- Re: Return two locations or low TTL [was: DNS caches that support partitioning ?] Mark Andrews (Aug 20)
- Re: DNS caches that support partitioning ? Aaron Hopkins (Aug 20)
- Re: DNS caches that support partitioning ? Andrew Sullivan (Aug 17)
- Re: DNS caches that support partitioning ? John Levine (Aug 17)
- Re: DNS caches that support partitioning ? Raymond Dijkxhoorn (Aug 18)
- Re: DNS caches that support partitioning ? Patrick W. Gilmore (Aug 18)
- Re: DNS caches that support partitioning ? Tony Finch (Aug 20)