Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!KL.SRI.COM!LARSON From: LARSON@KL.SRI.COM (Alan Larson) Newsgroups: comp.protocols.tcp-ip Subject: Re: Domain resolver resets needed Message-ID: <12480413275.5.LARSON@KL.SRI.COM> Date: 23 Mar 89 23:57:41 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 35 Keith Petersen mentioned the need to update domain resolver caches, noting that it would be 5 days before hosts with domain servers know that they have made an address change. Not quite true. Some hosts will (randomly) have almost expired data in their local cache, this data will expire in less than five days. Other hosts that didn't have the address at all, will work instantly. In any case, this problem need not have occured. I include excerpts from two RFCs on the subject: - - - - From RFC1033, "DOMAIN ADMINISTRATORS OPERATIONS GUIDE" Most host information does not change much over long time periods. A good way to set up your TTLs would be to set them at a high value, and then lower the value if you know a change will be coming soon. You might set most TTLs to anywhere between a day (86400) and a week (604800). Then, if you know some data will be changing in the near future, set the TTL for that RR down to a lower value (an hour to a day) until the change takes place, and then put it back up to its previous value. From RFC1034, "DOMAIN NAMES - CONCEPTS AND FACILITIES" ... If a change can be anticipated, the TTL can be reduced prior to the change to minimize inconsistency during the change, and then increased back to its former value following the change. - - - - Alan -------