Underscore in subdomain does not allows login in IE

Question

I recently came across a very strange problem, i had installed a dotnetnuke 7.4.1 version on dev server

I kept the domain as dev_new.dnntest.com, after installation and site setup with all appropriate skins, when i ran site on different browsers it seemed to work well, however when i tried to login from IE, it just kept refreshing the page.

At one point i thought it would be the installation issue or skin issue, not debuggable as well, hence i made a brand new installation on the same server, this time i just gave a domain as dev.dnntest.com and it worked

Now again i pointed to the first domain, and again login stopped in IE, so now i am sure it's just because of underscore (_) in the domain that the login isn't working in iE.

Anyone has any clue is there any such specific settings, i am sure, we could require a sub-domain with underscore at some point of time, isn't it.

Answer 1

As specified in RFC 1123, host names cannot have underscores.

IE is stricter than many browsers about this, and doesn't store cookies for such hosts.