Highly available DNS is the way to have multiple physical servers on different IP addresses serve your site. This has two principal advantages: the failure of any one of these physical servers does not cause downtime and performance will be improved as the work is spread around.
In order to use the high-availability DNS you need to use a DNS provider which implements "CNAME-equivalent" functionality at the apex. The providers who are currently known to implement this functionality are:
- ALIAS at DNSimple
- ANAME at DNS Made Easy
- ANAME at easyDNS
- CNAME at CloudFlare
- ALIAS at PointDNS
- ALIAS record at Zerigo
Why is a CNAME not enough?
Because a CNAME of the apex violates RFC1033 and in practice is known to cause problems with some email services. Most Metro Publisher clients will want the apex to resolve to their Metro Publisher instance, ruling out using a RFC-compliant CNAME as a solution.
What to do once I use a compatible DNS provider?
This is the easy part ;) You need to use that provider's "CNAME-equivalent" functionality to alias the domains you wish to resolve to your Metro Publisher instance to the domain public.metropublisher.com.
NOTE: If you need to migrate DNS, please be aware that other services such as email could be affected in the migration.
Also, unfortunately some big DNS registrars such as GoDaddy, don’t yet support this feature. Please let them know that you require this feature.
For any questions regarding this feature, please submit a support ticket.