Are sub domain URL’s permitted

[EziBookingsAU]

Hi,

I have the following URL structure

[subdomain] . [Domain].com/?x=y

I have registered [domain] for twitter cards.

But when I validate above URL I get status 400. Bad request.

Are subdomains not allowed? Is there a workaround?

[EziBookingsAU]

I was getting status 400 bad request because I didn’t include “www” before the url