The answer is: It depends. :)
When you make use of round robin DNS your clients do recieve multiple
records. This is from a single hit to www.microsoft.com and shows the dns
cache on the local machine.
www.microsoft.com.
------------------------------------------------------
Record Name . . . . . : www.microsoft.com
Record Type . . . . . : 5
Time To Live . . . . : 7124
Data Length . . . . . : 4
Section . . . . . . . : Answer
CNAME Record . . . . :
www.microsoft.akadns.net
Record Name . . . . . : www.microsoft.akadns.net
Record Type . . . . . : 1
Time To Live . . . . : 7124
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . :
207.46.131.91
Record Name . . . . . : www.microsoft.akadns.net
Record Type . . . . . : 1
Time To Live . . . . : 7124
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . :
207.46.230.229
Record Name . . . . . : www.microsoft.akadns.net
Record Type . . . . . : 1
Time To Live . . . . : 7124
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . :
207.46.230.218
Now, just because the host recieves this information, doesn't mean that the
host will USE all this information. YMMV, VWPBL, TOSTCAAT. And this only
addresses redundancy near the top of the OSI model. You are also looking to
make redundancy happen at the bottom, and that's why you have two T-1s, and
you've gotten some good answers on that. And if it's so bloody important,
you probably will be wanting to put in some redundancy at the server as
well, perhaps Win2K Network Load Balancing or something from the *nix world.
And remember, always ask 'What happens if Mars explodes?'
TTFN,
Bill in Anchorage
-----Original Message-----
If the ISP dies then, yes you'll lose both sites, but the world is a single
point of failure.
I believe the problem with the DNS solution is that although a DNS TTL can
be set to 0, there is only a requirement to support TTL down to 2 days. So
DNS info can be cached for this period by non-authorative DNS'.
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=7540&t=7511
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