Should secondary uri for a blob just work?

In C# you can grab the primary URI off a blob as well as the SecondaryUri. The secondary URI appears to be the same as the primary except with a modified subdomain. `https://examplecloudstorage.blob.core.windows.net/... vs https://examplecloudstorage-secondary.blob.core.windows.net/...`

I'm finding the while the primary uri works fine, the secondary returns a DNS error not found. Is there something special that needs to be done to enable the secondary URI on a blob or container?