Clarification on fixed-address statement

doug doug at
Fri Apr 29 20:17:50 UTC 2011

If the address is included  a range statement it will be handed out as 
the fixed address code is separate from the dynamic address code. use 
multiple range statements skipping any address used in fixed address 

On 04/29/2011 03:06 PM, Jack Kielsmeier wrote:
> Hello,
> We are running ISC DHCP 3.1.0 in a failover configuration. I do know
> that 3.1.0 is a somewhat old version, but it has worked well for us.
> I am wondering if this is the expected behavior of fixed-address
> statements:
> Upon initial inspection, it seems that if you declare a fixed-address
> for a MAC address, that IP address is reserved and can only be used by
> the declared MAC address.
> In reality, we are seeing the DHCP server hand out fixed-addresses to
> any MAC. When the MAC address that is assigned the fixed-address asks for
> an IP, DHCP will attempt to give it the fixed-address if it is free, but
> will hand out another IP if it's unavailable.
> Is this how fixed-address statements are supposed to work? If so, is
> there a way to make sure only a specific MAC address can use a specific
> IP address?
> For reference, this is how we are declaring fixed-addresses:
> host HOSTX { hardware ethernet xx:xx:xx:xx:xx:xx;fixed-address
> ###.###.###.###; }
> I have stripped the MAC and IP address out.
> Thank You,

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