Why won't root domains in Azure Traffic Manager load balance or fail over?

2
votes

Simply put:

I have a domain called erik.com, two azure websites (east and west), and one traffic manager that is setup to manage the two azure websites.

When I take east offline (by throwing a non-2** status code) erik.com goes offline. This should not be the case! Right?

However, when I add a sub domain to the two azure websites (www.erik.com) then it works! I take one or the other offline and the traffic manager resolves to the available website.

I'm hearing/reading things that tell me that Traffic manager doesn't work with root domains like that... Say what?! Why?

1
azuresubdomainazure-web-app-servicefailoverazure-traffic-manager
Well, I wouldn't mind answering, but we would really need to see how you have Traffic Manager configured. It really is not supposed to bring the whole service down, could also be just that it's still serving you the one you took down because TTL didn't expire yet? – juunas

1 Answers

5
votes

As explained in the FAQs at https://azure.microsoft.com/en-us/documentation/articles/traffic-manager-how-traffic-manager-works/#faq , Traffic Manager does not support 'naked' / apex domain names.

*Can I use Traffic Manager with a ‘naked’ (www-less) domain name?

Not currently.

The DNS CNAME record type is used to create a mapping from one DNS name to another name. As explained in the Traffic Manager example, Traffic Manager requires a DNS CNAME record to map the vanity DNS name (e.g. www.contoso.com) to the Traffic Manager profile DNS name (e.g. contoso.trafficmanager.net). In addition the Traffic Manager profile itself returns a second DNS CNAME to indicate which endpoint the client should connect to.

The DNS standards do not permit CNAMEs to co-exist with other DNS records of the same type. Since the apex (or root) of a DNS zone always contains two pre-existing DNS records (the SOA and the authoritative NS records), this means a CNAME record cannot be created at the zone apex without violating the DNS standards.

To work around this issue, we recommend that services using a naked (www-less) domain that want to use Traffic Manager should use an HTTP re-direct to direct traffic from the naked domain to a different URL, which can then use Traffic Manager. For example, the naked domain ‘contoso.com’ can re-direct users to ‘www.contoso.com’ which can then use Traffic Manager.

Full support for naked domains in Traffic Manager is tracked in our feature backlog. If you are interested in this feature please register your support by voting for it on our community feedback site.*