[NTLUG:Discuss] Use DNS for redundant geographic sites?

[Craig Gill]

Hey Neil,
Another solution is to have your dns hosted, Netriplex does geographically
disperse dns hosting and dns failover pretty cheaply, and their dns is
any-casted.

Craig

> Hello:
>
> I am trying to figure out a way to create a web site
> that is multi-homed geographically.
>
> I just thought of this idea:
>
> I will have two machines, each located in
> a different place.
>
> Machine A will run:
> 	dnsA.jammconsulting.com (DNS server)
> 	webA.jammconsulting.com (Web Server)
>
> Machine B will run:
> 	dnsB.jammconsulting.com (DNS server)
> 	webB.jammconsulting.com (Web Server)
>
> Now, lets assume that I register a new domain
> name.  For discussion, lets use jammconsulting.com
> as the domain name.
>
> In the domain records, I set the DNS servers to
> be:
> 	dnsA.jammconsulting.com
> 	dnsB.jammconsulting.com
>
> Now, here is the strange part:
>
> dnsA will always resolve www.jammconsultng.com to
> the IP address of webA and dnsB will always resolve
> www.jammconsulting.com to the IP address of webB.
>
> This way, if either machine goes down, the machine
> will not respond to DNS queries.  The DNS will query
> the other machine and all traffic will go to it.
>
> I know this does not protect me against the situation
> where dnsA is up and webA is down, but as long as
> the machine is up, I can set up monitoring of the
> web server.  Usually, Apache httpd runs without a
> problem.
>
> Will DNS clients handle a situation where the
> nameservers give different responses?
>
> Are there other downsides I have not considered?
>
> Thanks,
> 	Neil
>
> --
> Neil Aggarwal, (214)986-3533, www.JAMMConsulting.com
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>
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