Re: Adding another DHCP Server

Jorge,

A lot of good information. I'm still confused about one thing, though. If I
have 2 DHCP serves configured for the 50/50 rule, What happens if a client
accesses, say, DHCP1 and DHCP1 has run out of addresses to assign. Will the
client get an address from DHCP2 or will there be an error?

--
Regards,
Hank Arnold

"Jorge_de_Almeida_Pinto" <UseLinkToEmail@xxxxxxxxxxxxxxxxxxxxx> wrote in
message news:1454386_5c0f9664285dd3786d896f72df17e1f7@xxxxxxxxxxxxxxxxxxxx
>
> For distributing scopes among multiple DHCP servers two well known
> rules are available.
>
> Google for (only the text before the =):
> 50/50 dhcp = (central setup)
> and
> 80/20 dhcp = (local and remote setup)
>
> You should make sure only one DHCP servers leases a certain IP address
> otherwise you could get IP conflicts. DHCP Servers do
>
> not share the DHCP db, only when clustered.
>
> If one or more DHCP servers service the same set of clients you
> should, if applicable:
> (1) configure reservations on all those DHCP servers
> (2) Distribute available addresses among the DHCP servers
>
> (1)
> if you have clients that use DHCP reservations and you also have
> multiple DHCP servers that service those clients, you need
>
> to configure the DHCP reservations on all DHCP servers that service
> those clients as you want to make sure that independed of
>
> the DHCP server the client gets its reserved IP address
>
> (2)
> Depending on the distribution factor as mentioned above you need to
> make sure IP addresses are not leased more than once to
>
> any other client. Let me give me an example....
> Lets say you have a scope with the following AVAILABLE IP
> addresses.... A B C D E F G H I J (from A to J) and you have server
>
> DHCP1 and server DHCP2 as DHCP servers.
> You have the following possibilities:
> (A) configure the complete scope "A B C D E F G H I J" and enable it
> on both DHCP servers DHCP1 and DHCP2 and enable conflict
>
> detection so that each DHCP server first checks a certain IP address
> has not been leased by the OTHER DHCP server. (This is
>
> not a best practice and thus not recommended)
> (B) configure the complete scope "A B C D E F G H I J" and enable it
> on DHCP server DHCP1 and disable the scope on DHCP
>
> server DHCP2 (and enable conflict on the DHCP server that is made the
> servicing DHCP server while the other is not because it
>
> is unavailable or so) (this will work but if the first DHCP server
> becomes unavailable you need to enable conflict detection
>
> on the other DHCP servers and enable all of its scopes manually)
> (C) If you use the 50/50 rule (otherwise configure
> accordingly),configure half of the scope "A B C D E" on the DHCP
> server
>
> DHCP1 and configure the other half on DHCP server DHCP2 "F G H I J"
> and enable the scopes. Conflict detection is not needed
>
> here. The problem with this is that if the client switches from DHCP
> server the other DHCP server will issue a NACK because
>
> the client if trying to renew an unknown IP address to that DHCP
> server.
> (D) configure the complete scope "A B C D E F G H I J" and enable it
> on both DHCP servers DHCP1 and DHCP2.Conflict detection
>
> is not needed here. If you use the 50/50 rule (otherwise configure
> accordingly), on the first DHCP server DHCP1 exclude "A B
>
> C D E" and on the second DHCP server DHCP2 exclude "F G H I J" If the
> client switches from DHCP server the other DHCP server
>
> will not issue a NACK because it knows of the IP address although
> excluded (This is my preferred configuration and if also a
>
> best practice)
>
>
> Also remember:
> If secure DDNS updates are done by the DHCP server on behalf of the
> clients and more than 1 DHCP server services the same
>
> clients make sure each DHCP server is able to update the records. For
> this configure credentials on the DHCP server to
>
> acchieve this.
> If DHCP service is hosted on a DC, for security purposes you should
> configure DHCP with additional credentials to register
>
> records on behalf of the clients.
>
> If it is a W2K DHCP server you can only use the command line to
> configure credentials (NETSH DHCP...)
>
> If it is a W2K3 DHCP server you can use the command line and the GUI
> to configure credentials
>
> For more info see:
> *
> http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/ServerHelp/d0e19b57-c368-46c2-b017-caf25ae150ec.mspx
> * http://www.jsifaq.com/SUBN/tip6900/rh6941.htm
> *
> http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/ServerHelp/179d4f6c-9482-4dac-8f03-74bd78b7d263.mspx
>
> --
> Posted using the http://www.windowsforumz.com interface, at author's
> request
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> Topic URL: http://www.windowsforumz.com/Adding-DHCP-ftopict432590.html
> Visit Topic URL to contact author (reg. req'd). Report abuse:
> http://www.windowsforumz.com/eform.php?p=1454386


.

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