how many instances of x are there in:
q: windows domain authentication using host files i am currently setting up remote office pcs running windows 7 professional to authenticate back to a domain controller running windows 2008 r2 in the headquarters. is it possible to simply define the domain name of the domain controller using the local pcs hosts file instead of having to query a dns server?

a: unfortunately, no.  the hosts file is only a suitable replacement for proper dns when you need host (a) records and their associated reverse lookup (ptr) records.
active directory also requires a bunch of srv records to function, which you can see in your dns setup under the _msdcs.mydomain.com dns zone; these records cannot be set up with just a hosts file.
this article documents the necessary non-host records (in the context of setting up a bind server to serve them)

a: i know this is dead-thread revival, but here goes. according to
https://technet.microsoft.com/en-us/library/cc959846.aspx
and
https://support.microsoft.com/en-us/kb/180094
you can add entries in an lmhosts file for the domain controller. the file resides at c:\windows\system32\drivers\etc and is called lmhosts (no extension). the format for the domain controller entry is:

10.0.0.1   pdcname   #pre #dom:domain-name
10.0.0.1   domain-name    \0x1b   #pre


user
There are 4 "x"s in the text you provided.
assistant