On 05/17/2012 12:28 AM, Greg Woods wrote: > On Thu, 2012-05-17 at 00:13 +0800, Ed Greshko wrote: >> when you do a look up on www.cnn.com it will return 4 IP >> addresses. Now, since bind would have that in its cache it wouldn't have to >> send out >> a query. What I don't know is if an application would make a request would >> the list >> be returned in the same order every time to the requesting application? In >> other >> words, if the TTL is not set low, would that defeat the round robin >> technique. > Unfortunately, there is no guarantee that a client resolver will > actually use the IP addresses in the order they are presented by the DNS > server. Nothing in the DNS spec requires them to do so.
Yeah.... I know there is no spec... I'm just expecting the clients to be "dumb" and take the first one in the stack. :-) :-) > >> Interesting things to investigate.....if I really had the time. > My experience says that DNS round robining is actually a poor method of > load balancing. I'm surprised to see a large site like CNN resorting to > this (if that's really what they are doing this for). Perhaps in > combination with a low TTL and a modified DNS server, they can send out > a completely different set of IPs every few minutes, and achieve a sort > of crude load balancing that way, but I think load balancing works > better if you just send out a single IP and use a load balancer that you > can control, such as LVS (Linux Virtual Server) that can farm out > incoming connections to a single virtual address out to multiple real > addresses. Yes... I suppose one also has to ask if the load balancing is meant to be server or network balancing. -- Never be afraid to laugh at yourself, after all, you could be missing out on the joke of the century. -- Dame Edna Everage -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
