AlecZ64

Q: With multiple IP ranges in OS X DHCP server, which clients get assigned to what range?

In the DHCP management in El Capitan OS X Server, you can set up a DHCP service with multiple IP ranges.

 

E.g. I have these ranges, all with the same search domain:

192.168.1.2 - 192.168.1.35

192.168.1.36 - 192.168.1.90

192.168.1.90 - 192.168.1.100

 

If I do that, when a client takes a DHCP lease, which range is used? In other words, what IP address would a client get?

Posted on Jul 17, 2016 11:58 AM

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Q: With multiple IP ranges in OS X DHCP server, which clients get assigned to what range?

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  • by chattphotos,

    chattphotos chattphotos Jul 19, 2016 11:26 AM in response to AlecZ64
    Level 4 (2,412 points)
    Desktops
    Jul 19, 2016 11:26 AM in response to AlecZ64

    What's your subnet mask?

    Right now, the list you've provided isn't possible.

     

    Can you start with explaining why you're wanting to split a subnet into distinct sections?

     

    Have you considered doing IP reservations on a single /24? (192.168.1.1 - .255)

  • by AlecZ64,

    AlecZ64 AlecZ64 Jul 19, 2016 11:34 AM in response to chattphotos
    Level 1 (23 points)
    Mac OS X
    Jul 19, 2016 11:34 AM in response to chattphotos

    Sorry, I guess I should've provided my actual ranges instead of an example that I thought was equivalent. This is what I have, and it's valid:

     

    10.0.1.2 - 10.0.1.190

    192.168.1.2 - 192.168.1.190

    subnet mask 255.255.255.0

     

    I'm doing this because we've got two routers clients are connecting to, and if I enable DHCP on both routers, we get a race condition and possibly other problems. I'm trying to replace the two routers' DHCP services with just the OS X Server DHCP service.

  • by Phil0124,

    Phil0124 Phil0124 Jul 19, 2016 11:40 AM in response to AlecZ64
    Level 7 (26,872 points)
    iPhone
    Jul 19, 2016 11:40 AM in response to AlecZ64

    Your ranges are meaningless as they are.  As they end up being the same thing as a single range of  192.168.1.2 - 192.168.1.100

     

    Setting ranges means the IPs in those ranges get assigned by DHCP, so any client can get an IP in those ranges.

     

    If you have three contiguous ranges, that means all those IPs can be assigned to clients.

     

    In other words DHCP ranges are used to determine which IP addresses get automatically assigned to clients. IPs not in a range will not get leased to clients and will be left untouched.

     

    A DHCP server will only assign IPs in the range it exists on.  Your DHCP server unless it has 2 network adapters can only ever exist on one IP range. 10.x.x.x cannot be used on the same network adapter that is using 192.x.x.x