Any insight on this. We are looking for a backup site solution.

As i understand you would have a primary and secondary dns server. If one server goes down then it will go to the second dns server to look for host information. THis then will point to backup hosting server.

this way you would really need 3 dns servers. 1 primary in primary location. 1 secondary in primary location and 1 primary in secondary location.

as far as the domain registrar you would enter all 3 in order of search. ex: ns1. ns2. and ns3.

does this sound like the right idea?

as far as replicating servers Im assuming you would need software to do this through ftp. Any suggestions?

As i understand you would have a primary and secondary dns server. If one server goes down then it will go to the second dns server to look for host information. THis then will point to backup hosting server. as far as the domain registrar you would enter all 3 in order of search. ex: ns1. ns2. and ns3. DNS clients pick one of the listed servers, send a query to it, and if it doesn't respond, repeats with another DNS server in the list. You do not have control over which server a DNS client picks first, so all DNS servers must answer with the same data, or you'll get inconsistent results. For a DNS-based solution, it's possible to use low TTLs and if the primary server fails, you can modify DNS to point to the backup server.as far as replicating servers Im assuming you would need software to do this through ftp. Any suggestions? Instead of FTP, I'd use rsync over SSH to mirror files.

There's a recent thread asking a similar question: www,webhostingtalk,com/showthread.php?t=474534
waxdoll contradicts the DNS answer I gave.

you wrote:

For a DNS-based solution, it's possible to use low TTLs and if the primary server fails, you can modify DNS to point to the backup server.

How would you do this then? Is there a setting to change in the dns entry?

you wrote:
How would you do this then? Is there a setting to change in the dns entry?

Are you actually providing hosting services?!

yes we do.

As of right now we use have 2 dns servers in each location. I primary and secondary.

we also replicate each server using dfs and frs.
we use ad for user management so all accounts are replicated throughout the servers.

if one site was to go down then our secondary site would take over.

obviously all sites are behind a hardware firewall.


I was just lookign to see how everyone else was doing it.

this solution works for us. WIndows 2003 r2 now has dfs with delta. definitely worth checking out for those of you who are still looking for an answer.

How would you do this then? Is there a setting to change in the dns entry?
For example, if your primary server is 192.168.250.1 and your backup is 192.168.251.1, while your primary server is running, you'd have the DNS entry:
server.domain.com. 900 IN A 192.168.250.1,
and when the primary server fails, you want to change it to:
server.domain.com. 900 IN A 192.168.251.1

You will need to be able to modify DNS entries with the primary server down, so this may require making your backup server a master DNS server either now or when the primary server fails.

I run Linux, so I'd use an nsupdate script to change the DNS entries:
#!/usr/bin/nsupdate -vk keyfile
server 192.168.251.1
update delete server.domain.com. IN A
update add server.domain.com. 900 IN A 192.168.251.1
send