nanog mailing list archives
Re: Return two locations or low TTL [was: DNS caches that support partitioning ?]
From: Mark Andrews <marka () isc org>
Date: Tue, 21 Aug 2012 10:05:00 +1000
In message <20120820124734.GA14383 () hiwaay net>, Chris Adams writes:
Once upon a time, Patrick W. Gilmore <patrick () ianai net> said:* How many applications are even aware multiple addresses were returned?Most anything that supports IPv6 should handle this correctly, since getaddrinfo() will return a list of addresses to try.* How do you guarantee sub-second failover when most apps will wait longer than one second to see if an address responds?That's a bigger issue. Also, for web services, the application might wait, but the end-user usually won't (if the site doesn't come up in a second, they move on to the something else).
You file RFE / bug reports against the clients for having crappy fail over behaviour. It isn't hard to write TCP based code that falls over to the next available server. You don't have to wait for connect to fail before you attempt to connect to the next address. You just use a smarter connect loop. UDP code is a little harder as the work needs to more spread though the code than just replacing the dumb connect loop with a smart connect loop. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka () isc org
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 ?] Tony Finch (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 ?] 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)