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We have a site in London which has a slash 8 subnet. We're setting up a second site in Glasgow and we want people to authenticate to Glasgow who are based in Glasgow.

My question is how do we split the subnet from London so users retain the same IP addresses in Glasgow, if that possible?

Is tere an easy way to split the current subnet to accomodate the new site so people who authenicate in Glasgow can use the london servers if something in Glasgow went wrong.

Thanks in advance

Norrin Rad
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  • http://serverfault.com/questions/49765/how-does-ipv4-subnetting-work – HBruijn Jun 14 '16 at 07:22
  • it's unclear what you mean by "how do we split the subnet from London so users retain the same IP addresses in Glasgow" – hobbs Jun 14 '16 at 07:31
  • Sorry what I'm trying to work out is if Glasgow loses the dcs then the users can still authenticate in London. So I assume they need to be on the same up range otherwise how would they see London network.. – Norrin Rad Jun 14 '16 at 07:37

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Sorry what I'm trying to work out is if Glasgow loses the dcs then the users can still authenticate in London. So I assume they need to be on the same up range otherwise how would they see London network..

Your comment reveals the basic misunderstanding you've made. There's no requirement for the client and the DC to be on the same subnet. You use a separate subnet for each site and run a VPN between them. You then configure Active Directory Sites for each location. Clients will prefer their local DC, but if you lose the local DC they will authenticate against the remote DCs across the VPN.

I don't understand what you mean by splitting the /8 and retaining the same IP addresses, so I can't comment on that.

BlueCompute
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