username challenge when browsing to: \\domain.local

I have a 2008 R2 domain with two sites. Each site has 2 DC's.  Several windows 7 computers have difficulty browsing to: \\domain.local to enumerate the listing of shares on that server (Sysvol & Netlogon).  There is a username/password challenge request that pops up.  However, when browsing to \\dc1.domain.local, I do not get a username/password challenge request.  I find that pretty odd. Would there be different authentication mechanisms between "\\dc1.domain.local" and "\\domain.local"?

Thanks