RoundRobin DNS?

Len Conrad LConrad at
Wed Jun 12 19:14:50 UTC 2002

>     This is a first time I get a client big enough that needs this 
> solution.  Imagine a scenario, that you have a web server that can't go 
> down.  So you put it up at 2 different locations, say one in LA, other in 
> NYC.  So if say the ISP in LA goes down, NYC should theoretically start 
> getting requests for webhits.  That's what this client wants.  So how is 
> this done, I'm not sure this is done with DNS at all, although its a 
> possibility.  When I querry with nslookup, I get a few 
> different ips. HOW IS THIS DONE?   Can someone please point me in the 
> right direction?

DNS can do blind load distribution by varying the physical order of records 
in an RRset (eg, multiple ip's for a www.domain/IN/A query).  But there is 
in failover since visitors will be sent to an ip even if the web server is 

RAD Linkproof box (eBay, about $2k) can do intelligent load-balancing.  The donmain is delegated to the Linkproof which responds to A 
queries (but is not a full DNS) and which passes out short TTL A records 
based on the Linkproof's evaluation of the response www servers.

Also google for fezhead.

Len : DNS Training : ISC BIND for NT4 & W2K  : Build free, hi-perf, anti-abuse mail gateways

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