two DHCP server problems

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fran1942

82 posts

Master Geek

Trusted

#157359 28-Nov-2014 14:42

if you inadvertently have two DHCP servers on a network both making DHCP offers, will this cause a client to refuse both or will take it an offer from the first it receives ?
I have a situation like this, but my client is not taking on any address.

Thanks kindly.

nathan

5695 posts

Uber Geek
Inactive user

#1184920 28-Nov-2014 14:44

first one replying wins

Mattmannz

471 posts

Ultimate Geek

#1184932 28-Nov-2014 14:56

On the client that isn't getting an address run wireshark and capture the traffic. You should see both offers and see what the client is doing in respect to the offers.

russelo

328 posts

Ultimate Geek

#1184933 28-Nov-2014 15:02

you may end up with two clients having same ip address.

nathan

5695 posts

Uber Geek
Inactive user

#1184938 28-Nov-2014 15:08

russelo: you may end up with two clients having same ip address.

some can now ping the addr before handing it out to a client to "check" to see if its in use

Mattmannz

471 posts

Ultimate Geek

#1184960 28-Nov-2014 15:20

It's common to have multiple DHCP servers servicing a particular segment. Ensure that the scopes don't overlap by much if possible.

qyiet

454 posts

Ultimate Geek

Trusted

#1185016 28-Nov-2014 16:34

Mattmannz: It's common to have multiple DHCP servers servicing a particular segment. Ensure that the scopes don't overlap by much if possible.

Reallly? I've never seen it. I can see the mechanics working with non-overlapping scopes, but I can't see why you would do it otherwise.

Warning: reality may differ from above post

jnimmo

1097 posts

Uber Geek

#1185029 28-Nov-2014 16:49

For redundancy i.e. if one DHCP server goes down.

What environment are we talking here, Windows servers or misc routers?

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Regs

4066 posts

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Snowflake

#1185132 28-Nov-2014 21:04

windows server 2012 r2 can have two DHCP servers serving the same scope for load balancing (active/active) or failover (active/passive).

check out the TechNet article on DCHP Failover: http://technet.microsoft.com/en-us/library/dn338979.aspx

you can also check out the Microsoft Virtual Academy jumpstart for Windows Server 2012 R2 to catch all the new/updated features, or check out the session from the various TechEd events on Channel 9.

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