"Windows Azure Domain Name System (DNS) is moving to a new globally distributed infrastructure, which'll increase performance and improve reliability of DNS resolution. In particular, users who access Azure apps from outside the United States will see a decrease in the time it takes to resolve the apps' DNS names. This change will take effect on October 5th, at midnight UTC. Customers don't need to do anything to get these improvements, and there'll be no service interruption during the changeover.
"Because of inherently distributed nature of this new global infrastructure, creation of new DNS names associated with a Azure app can take up to two minutes to be fully addressable on a global basis. During this propagation time, new DNS records will resolve as NXDOMAIN. If you attempt to access new DNS name during this time window, most client computers will cache these negative responses for up to 15 minutes, causing "DNS Not Found" messages. Under most circumstances you'll not notice this delay, but if you promote a Azure staging deployment to production for a brand new hosted service, you may observe a delay in availability of DNS resolution," explained Microsoft.