RoundRobin DNS?

List User listusr at
Wed Jun 12 19:29:55 UTC 2002

also cisco makes a box called distributed director which has multile
functions one being this global redundancy via BGP metrics or meds also
just plain old redundancy via the dns server within the distributed
director.  it tests the port that should answer on all the web servers
around the world if one is down it removes it from the zone it has for the .  pretty cool product especially for BGP metric balancing and
having your client go to the closest server.

On Wed, 12 Jun 2002, Len Conrad wrote:

> >     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 
> down.
> 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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