On Thu, 4 Jun 1998, Dean Anderson wrote: ) At 2:51 PM -0400 6/3/98, Phillip Vandry wrote: ) >> 2. Why Web services don't have entries like MX hosts do. Why not be able to ) >> set preferences and fall over hosts? ) Err, they do. Here's how to set it up: These balance the load, and if one ) machine is down, any browser which handles multiple A records properly will ) still fail over to the other machine. ) ) www IN CNAME www1.av8.com. ) IN CNAME www2.av8.com. That's a Very Bad Idea(tMS). CNAMEs are used as aliases, direct mappings. For the same reason you can't CNAME a zone's root to something else (meaning, if I am setting up the zone map for n.ml.org, I can CNAME web.n.ml.org to narnia.n.ml.org, but I can't CNAME n.ml.org to narnia.n.ml.org, nor can I CNAME n.ml.org to ftp.microsoft.com, or any other host), you cannot use multiple CNAMEs. You can *physically* CNAME multiple times, but you're likely to break things, as it's against the rules. What you're in fact doing is aliasing one host to two different ones, which doesn't make sense (because a CNAME says that ThisHost is actually just a pointer to ThatHost). ) www1 IN A 198.3.136.144 ) IN A 208.156.100.250 ) www2 IN A 208.156.100.250 ) IN A 198.3.136.144 That seems rather redundant. Just stick www1's IN A's into www, and forget about www1 and www2 and funky multiple CNAMEing. There's no need to handle rotations of the IN A's yourself--BIND, at least, does it all for you. Do an nslookup on irc.dal.net a couple times, or us.undernet.org. Each time you do it, the IP's are shifted over to the left by one. Hence, a user doing /server us.undernet.org might get connected to LasVegas.NV.US.Undernet.org, while the next person who does /server us.undernet.org will get connected to Arlington.VA.US.Undernet.Org. ) (What? Your browser won't use multiple A records? Well, in that case, it ) probably will be a much longer time before it supports a new DNS record ) type.) "Supporting" multiple IN A's shouldn't be necessary for a client to take advantage of multiple IN A's. Since the IN A's are rotated, load balancing is implemented at the nameserver level. The client should just always connect to the first IN A given to it. -- Daniel Reed <n@ml.org> (ask me for my PGP key) If a jury in a criminal trial stays out for more than twenty-four hours, it is certain to vote acquittal, save in those instances where it votes guilty -- Joseph C. Goulden