stop users authenticating to a domain controller

i have 6 domain controllers 2 of which are old but the admins of the site is also using them as a file server. what i would like to do is stop all users from authenticating to the two old ad servers they are 2008 standard servers. the four new ad servers are 2012. i was looking into LdapSrvPriority registry entry but neither 2008 or 2012 has the reg entry. so would i have to create the reg entry on all 6 and give the four new servers a lower weight or can i just give the two old ones a weight of 100 and move on.
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Peter HutchisonSenior Network Systems SpecialistCommented:
The best thing to do is demote the old DCs to member servers. Run DcPRomo to remove the Domain Services role.
Toni UranjekConsultant/TrainerCommented:
No need to edit registry. Just edit priority for SRV records on one DNS server and you are done.
CecilpierceAuthor Commented:
yes i understand that and that will be the intended fix in the end, the issue is we are having AD and GPO replication issues with 2 old servers and i thought there would be a quick way to just stop users from logging onto these 2 server and that would give me the time to address the removal later
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CecilpierceAuthor Commented:
Toni Uranjek
would that be msdcs+dc+sites+site name+tcp+ select property's on ladp and set priority to a number higher than 0?
Toni UranjekConsultant/TrainerCommented:
_kerberos records priority should be sufficent.

Kerberos record is your point for authentication.

Priority: As for MX, the priority of this target host. A client must attempt to contact the target host with the lowest-numbered priority it can reach; target hosts with the same priority should be tried in pseudorandom order. The range is 0-65535.

From this article:
Description of the DNS SRV Resource Record Type
CecilpierceAuthor Commented:
I've requested that this question be closed as follows:

Accepted answer: 0 points for Cecilpierce's comment #a41027160

for the following reason:

perfect this is what i was looking for
Toni UranjekConsultant/TrainerCommented:
Mate, I thought my posts were helpfull? :D

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CecilpierceAuthor Commented:
i thought i awarded this to you already
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Windows Server 2008

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