March 26th, 2012, 02:33 PM
Disaster Recovery situations
I've been searching the net and haven't really found a solution yet. We are a web hosting company and are in the midst of a project for disaster recovery. Currently, our entire solution is in one datacenter and we plan to setup another site for DR situations. Our application has 100's of DNS entries and this is the plan that I think is the only solution:
1. Create an A record for all the primary sites. Say cname.test.com pointing to 2 load-balanced IP's (one in primary location, second one in DR site). The secondary would have all services disabled on the DR load balance so all traffic goes to one site.
2. CNAME all client subdomains to cname.test.com
3. Now, this is where my question is. Since you shouldn't CNAME the top level domain, we would redirect it to the WWW counterpart. So, in essence, we would need to create the same A record as cname.test.com where the root level domain would have 2 A records. Is there any way around this?
I've been reading about global load balancers, but even then, it seemed to have some holes on response time, etc.
I think part 1 and 2 is fine. I'm curious as to how to provide a solution for #3. Let's say we decide to make some IP changes - I wouldn't want to go through the process of changing all those DNS entries again.
March 26th, 2012, 06:31 PM
Could you create a site-to-site VPN connection from the primary locaiton to the DR locaiton; then have DNS replicate from one to the other on the fly? You could then have the DNS server(s) at the DR location be authoirative NS for those domains. This would allow DNS to replicate across both servers, and if one goes down, your clients should still be able to get DNS information from the other server? You would however have to allow the DNS server service to run for this to work.
March 27th, 2012, 10:01 AM
DNS hosting is not really the problem (our co-lo has it setup and they have their name servers in different locations). My problem is, we have 100's of URL's and if we ever needed to make a change, we could change the CNAME to point to a different set of IPs, however the non-WWW URL's would not be reflected. I don't want to go through 100's of zones manually modifying each non-WWW A record. So imagine the following (note, I changed all periods with a '_')
cname_test_com A 11_11_11_11
www_test1_com CNAME cname_test_com
test1_com A 11_11_11_11
www_test2_com CNAME cname_test_com
test2_com A 11_11_11_11
Let's say I need to change the IP, I can easily change cname_test_com to point to say 22_22_22_22
How could I update test1_com and test2_com in one shot as opposed to updating them manually?
March 27th, 2012, 05:34 PM
I'm afraid you're getting a little outside my expertise on this one. Maybe Adam our Doug can chime in here.