In message <barmar-1baa23.22544006112...@news.eternal-september.org>, Barry Mar golin writes: > In article <mailman.1.1320621651.68562.bind-us...@lists.isc.org>, > Chris Thompson <c...@cam.ac.uk> wrote: > > > On Nov 5 2011, Alan Clegg wrote: > > > > >On 11/5/2011 4:21 AM, kalpesh varyani wrote: > > >> How does this feature address the risk that data provided by one master > > >> might get overwritten by another? > > > > > >The use of the word "masters" in the configuration of a slave zone is a > > >bit misleading. Under most circumstances, you list the authoritative > > >servers, not "multiple masters". > > > > Although Alan doesn't say so, this might suggest to some that you should > > list *all* the authoritative servers. That's a very bad idea - you need > > to arrange that the directed graph of "A can fetch from B" is acyclic. > > Otherwise servers can get into the state that A thinks its copy of the > > zone is up to date because B told it so, and B thinks so because A told > > it so (or longer loops, of course), while neither of them are true masters > > for it. > > I don't think it's a problem. As long as ANY of the servers in the > masters list have a higher serial number, you'll fetch from it. > > So if you have three servers, A, B, and C, A will check the serial > numbers on both B and C, and pull from whichever has a higher serial > number than the serial A already has.
Transfer graph loops prevent expire working as a safeguard against loss of connectivity to the master source. They are not a issue with respect to gettting the latest version of the zone. If M is the ultimate master and A and B transfer from each other and M, when M dies, the SOA queries A to B and B to A succeed causing each of A and B to believe the its current zone contents as they will both be serving the zone with the same serial. I proposed a solution but couldn't get traction with the dnsext working group. http://tools.ietf.org/html/draft-andrews-dnsext-expire-00 Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
