ok..if this is the new dc .. and has already registered its srv records in the dsn server .. (to test check RReg test results of the comand dcdiag /test:dns )
the clients my be still using the old dc.. for that you need to do ipconfig /flushdns on the clients so that they query dns for a dc in their site and dns gives this servers records to client for authentication
..
here is how log on process startd :
the dns service on workstation sends dns query to the dns server specified in the TCP/IP settings
and dns server give results according the site location requestd by client ..
if client does not specify any site.. dns give all dcs.. and client connects to random dc
howevr if the dc is in different site.. this dc will give the fqdn of dc client should be connection to ..
now.. other case may be .. if SRV record proority and weight specified in dns
cleints connect to srv records with "lowest priority and highest weith " .. that is (0)(100) by default
if there is a dc with prioruty of 5 and weight of 100 and other dc has 0 and 100
the client will chose later dc ..as this has lower priority
check that if dcs in other site have srv records modified
