Technical References

Controls whether the DHCP server releases other leases a client
might have on other LAN segments on this server.
0 disabled
1 last-client-preferred
2 first-client-preferred
Within one LAN segment, the DHCP server never allocates more
than one DHCPv4 address to a single client. Across multiple
independent network LAN segments, however, a single client
might have one address allocated on several networks.
In an enterprise environment this might happen when a laptop
user travels from building to building, causing no particular
problems. In a service provider context, this might happen when
an unapproved user attempts to clone the MAC address of a
legitimate subscriber, causing a theft of service.
The one-lease-per-client feature limits a single client to one
lease over all of the networks configured on the DHCP server.
This limit only affects a client's ability to have concurrent
leases to different IP addresses on more than one network at
a time on the DHCP server.
In the last-client-preferred approach, the client with the most
recent lease is given preference, and any other leases held by
the same client are released.
In the first-client-preferred approach, the first lease that a
particular client receives from the DHCP server is the only
lease that client is allowed. In the event that the client
moves, the first lease must be made available (perhaps by a
force-available command or by letting it expire) before the
client is allowed to lease another IP address on a different
network.
Caution: Use the first-client-preferred approach with great
care, since manual intervention might be required to ensure
proper operation.
Both forms of one-lease-per-client require additional bookkeeping
overhead beyond that normally done in the DHCP server.
ping-clients bool default = disabled
Controls the default value of the Scope's 'ping-clients' attribute
if not explicitly configured on a scope.
This attribute allows the administrator to control the server
wide default for pinging an address before assigning it to a
client. It can be explicitly overwritten for each scope.
If enabled, see the 'ping-timeout' attribute as it may also
need to be set.
ping-timeout rangeint(0-10000) default = 300
Sets the server default for the number of milliseconds
the server waits for ping responses. If you make this value too
large, you slow down the lease offering processes. If you make
this value too small, you reduce the effectiveness of pinging
addresses before offering them. 300 milliseconds (the
default value) is often the best choice.
When ping-clients is enabled (either on a scope or server-wide),
this value is used as the default if not explicitly configured on
a scope.
priority-address-allocation bool default = disabled