Multisite domain mapping: No blog address to revert to when domain mapping is made inactive

[henry.wright]

When a user creates a blog in a network install they are given a blog address like "foobar.example.com". Now, imagine domain mapping is activated for this blog and the blog can be accessed using a custom domain like "example.com".

If the user decides they no longer want example.com to be hosted on the network, they may point DNS records to an IP address not associated with the network install. This will result in an orphaned blog because the "foobar.example.com" address was vacated when the initial domain mapping became active.

"foobar.example.com" isn't reserved so a completely different user may have created a new blog in the mean time using the "foobar.example.com" address.

[henry.wright]

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