After moving my site to WebHosting, why does a DNS record still point to metro?

This FAQ was last modified on: Tuesday, February 16, 2016 04:02pm
Category: 
If your domain is used to send or receive e-mail or if it is a DNS zone, it cannot be directly associated with webHosting.
 
In this situation, an HTTP redirect will be required to ensure that requests for your domain go to a DNS address associated with the webHosting server. This redirect is hosted on metro which is why the DNS record for your domain still points there. This is not an optimal solution and OIT is working on allowing these domains to point to webHosting. Until that is set up, the metro redirect will remain in place.
 
From a technical standpoint, a domain that sends or receives e-mail has MX records associated with it and a domain that is a DNS zone has at least a SOA record associated with it. In order to keep the e-mail and/or DNS zone functionality, the domain cannot be a DNS cname because a cname overrides all other records (including MX and SOA records) associated with a domain. These domains must be A records. 
 
Because webHosting is not set up as a single box (it is two machines... a primary and a DR fail-over), pointing DNS A records to web-plesk1.gatech.edu's IP (130.207.160.82) would be ineffective in the case where OIT has to switch to the back-up webHosting machine.
 
Any DNS entries for sites on webHosting that are cnames should be cnames to webhosting.gatech.edu, whose DNS is (eventually) served via GTM, and thus can be changed quickly, easily, and globally (for all sites on webHosting) in case of emergency.
 
Any DNS entries for sites on webHosting that must be A records (for reasons explained above), should point to one of metro's IP addresses, where a host entry will redirect the request to a cname pointed to webHosting. 
 

 
For example, ae.gatech.edu cannot be a cname because it has MX records. It must be an A record, and in this case, to metro's php5 interface:
 
# host ae.gatech.edu
 
ae.gatech.edu has address 130.207.244.37
 
ae.gatech.edu mail is handled by 10 mx2.gatech.edu
ae.gatech.edu mail is handled by 10 mx3.gatech.edu
ae.gatech.edu mail is handled by 10 mx4.gatech.edu
ae.gatech.edu mail is handled by 10 mx5.gatech.edu
ae.gatech.edu mail is handled by 10 mx1.gatech.edu

 

# host www.ae.gatech.edu
 
www.ae.gatech.edu is an alias for webhosting.gatech.edu
webhosting.gatech.edu is an alias for hosting1.gtm.gatech.edu 

 

hosting1.gtm.gatech.edu has address 130.207.160.82

 

 

Requests for http://ae.gatech.edu/ are sent to  130.207.244.37 (the php5 interface of metro) where they are redirected to http://www.ae.gatech.edu/ which is on webHosting.