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I know it could be very different based on the situation, but for hosting a website with no plans to move the hosting server what is a good TTL to set on the DNS record?

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6 Answers

up vote 12 down vote accepted

I tend to leave it at Slicehost's default, 86,400 seconds (1 day). I drop it down to 10 minutes when I have a move pending and wait a day or two.

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I'd just leave it at the default set by your host, unless it's ridiculously high or low for some reason. Then if you ever do want to move bump it down to 20 minutes or so a couple of days before you plan to do the move.

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4 hours should be just fine, providing an acceptable balance. That's what I use on most zones.

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That's probably way too short. –  dmourati May 17 '11 at 0:19
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@dmourati: It's 2011. For the overwhelmingly vast majority of small (i.e., under 1000 or so zones) DNS servers and for any and all clients the additional CPU load and bandwidth requirements are absolutely negligible. Of course, if your DNS servers go down for more than 4 hours you're SOL, but if that's important and you can't provide reliable DNS service you have no business hosting your DNS service on such a rickety foundation in the first place... –  Mihai Limbăşan Jun 7 '11 at 17:48
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When a user asks a question that is answered directly in an RFC you direct them to the RFC regardless of what year it is. –  dmourati Jun 21 '11 at 3:17
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1 Day is the recommended minimum default TTL as specified in RFC 1033.

http://tools.ietf.org/html/rfc1033

RFC 1912 goes on to say that 1 day is probably too short and 3 days may be more appopriate.

http://www.ietf.org/rfc/rfc1912.txt

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I'd imagine DNS traffic from low TTLs was significantly more of a problem in 1987 and 1996 than in 2011/2012. –  ceejayoz Nov 27 '12 at 22:33
    
Both those standards you quote are referring to the "Minimum" field of the SOA record only, which is no longer used for determining the default or minimum TTL anyway, as was intended back when those standards were written. DNS best practices written 27 and 18 years ago were written when DNS - indeed the internet - was a different beast. Nowadays, 300 seconds (5 minutes) is a fairly common TTL for main A/AAAA records, although only useful when needing fast failover otherwise 6 hours+ would be more appropriate. NS records, and the A/AAAA records for the NS addresses, are usually 1 day or more. –  thomasrutter Jun 7 at 16:02
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Besides RFC 1912, users in Europe should also see RIPE-203, "Recommendations for DNS SOA Values", which recommends two days as a minimum TTL value.

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I have noticed it is becoming more fashionable to have shorter TTLs to be able to respond in emergencies (particularly within HA DNS environments) quicker.

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