I have a question regarding dns prefetch of internal subdomains. Say i have a site spread ower several subdomains:
Will it give me any perfomance to do a prefetch of those subdomains? Like this:
<link href="//images.domain.com" rel="dns-prefetch" />
<link href="//shop.domain.com" rel="dns-prefetch" />
If you've determined that it would be useful to use dns-prefetch for some resources, there is no difference between a subdomain vs a completely independent domain in that case so I would use prefetch.
Each subdomain can contain completely different addresses, cnames, etc so from the perspective of the browser they are as different as any other domain.