title: Which is better for provisioning sub-domains on Azure - wildcard CNAME or an API-based DNS like Route 53?
body: <p>I am building an application on Azure that requires the use of subdomains for each customer.  Subdomains will be provisioned during the registration process.  Since Azure <a href="http://msdn.microsoft.com/en-us/library/ff803360.aspx" rel="nofollow noreferrer">requires the use of CNAME for DNS resolution</a>, I must decide between a wildcard CNAME or should I add each entry manually using an API such as <a href="http://aws.amazon.com/route53/" rel="nofollow noreferrer">Amazon Route 53</a></p>
  
  <p>I am concerned about wildcard CNames because <a href="https://serverfault.com/questions/44618/is-a-wildcard-cname-dns-record-valid">there is some question</a> of whether or not they are fully supported by all DNS systems.  I see that it is part of the RFC spec, but I am worried about how up to date all the DNS systems are.</p>
  
  <p>Alternatively, I'm worried about provisioning new CNAME DNS entries for customers in real time.   Would they have to wait for the TTL to expire, or would new subdomain CNAME entries be picked up immediately?</p>
  
  <p>Thanks,
  Doug</p>