Roberto C. Sanchez wrote: >> I want to purchase ANOTHER dedicated server and make it so that if on >> someone types in the browser www.eccotours.biz, obviously it will >> resolve to >> one of the IPs. BUT how will I handle if one of the machines is down. >> How can I get around this. >> Or will the client first try one IP, if on failure, try the next one. > What you want to do requires a front-end machine for load balancing, not > an additional IP/DNS setup. You would tell it to proxy traffic to one > of two (or more) machines that are up and running.
Well - it can actually be done with a little bit of clever DNS setup too and to the best of my knowledge completely acceptable from a DNS point of view. Imagine we want to configure 3 identical web servers and do a reasonable load balancing between them - AND make sure one of two of them can be down without too many users being annoyed. Let's use company.com as an example domain. We want to play with some NS records instead of A or CNAME records, so in the basic company.com zone we do two things - redelecate a sub domain AND do an alias - something along this line: web IN NS server1 web IN NS server2 web IN NS server3 server1 IN A xxx.xxx.xxx.xxx server2 IN A xxx.xxx.xxx.xxx server3 IN A xxx.xxx.xxx.xxx www IN CNAME www.web Ok - by now we have appointed our three servers as authoritative for the web.company.com domain and we point www to a server called www.web.company.com. Normally when configuring 3 name servers for a domain you would make a master and then slave the other two. In this case we do NOT do that - we make all three authoritative AND we make sure it's got a VERY short time to live (say 5 minutes). These zones will follow something like this: Server 1: --------- www IN CNAME server1.company.com. Server 2: --------- www IN CNAME server2.company.com. Server 3: --------- www IN CNAME server3.company.com. In other words what server we resolve to depends on which name server we asked and if one of the name servers disappear - nobody will ever point to that particular server. GRANTED - this is not bulllet proof. It does NOT protect against for example apache dying while bind is still running (but honestly - how often does that happen compared to an internet line being down?). Also - when a server or connection dies there WILL be a short period where users are pointed to the dead server. It does however provide a reasonable load balancing AND contrary to having a proper proxy it can be distributed across multiple internet or hosting providers. -- Lars -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
