DHCP reservation renewal

Hi,

I guess this is a very simple question but I couldn't really find any
documentation on it:
- clients that have a reservation in DHCP show up with a lease
duration of INFINITE in the address leases list
- usually a client tries to renew its lease after 50% of the lease
duration has expired. What's 50% of infinite? ;-)

Does the lease duration setting on the scope (e.g. 8 days) also apply
to the reservations?
If yes, does that mean that in this scenario the client should renew
its lease every four days? The DHCP server is configured to always
update A- and PTR-records.

I'm wondering because some printers connected through JetDirect cards
(with reservations) receive the correct addresses but it seems like
the DNS entries never get updated after they are initially created and
consequently are scavenged by the DNS server sooner or later. Turning
the printer on and off solves the problem but is not an option for us.

Thanks for your help
Chris

 

In

Mathematically speaking, 50% of infinite is infinite.

To optimize JetDirects registering in DNS, you can force DHCP to register
for clients that cannot register (DHCP properties, DNS tab), such as a
JetDirect, which can't update itself. But when DHCP renews the reservation
address, DHCP unfortunately can't update it on a renewal because it doesn't
own the record. When you restart, it's a new, fresh lease. To make it work,
you would need to add the DHCP server to the DnsUpdateProxy group. Read up
on it ->

How to configure DNS dynamic updates in Windows Server 2003 - scroll down to
"Use the DnsUpdateProxy security group:"
http://support.microsoft.com/kb/816592


As for Revervations, they follow the lease period. Clients renew at 50%
(half the lease time) and if not sucessful at 87.5% (7/8th of the lease
time). This allows clients wil reservations to pick up updated DHCP options
such as default gateway and DNS server information just like any other DHCP
client.

(scroll past the advertisements):
http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Server/2003_Server/Q_23168038.html

The following is quoted from DHCP RFC 2131:
http://www.ietf.org/rfc/rfc2131.txt

2.2 Dynamic allocation of network addresses

The second service provided by DHCP is the allocation of temporary or
permanent network (IP) addresses to clients. The basic mechanism for
the dynamic allocation of network addresses is simple: a client
requests the use of an address for some period of time. The
allocation mechanism (the collection of DHCP servers) guarantees not
to reallocate that address within the requested time and attempts to
return the same network address each time the client requests an
address. In this document, the period over which a network address
is allocated to a client is referred to as a "lease" [11]. The
client may extend its lease with subsequent requests. The client may
issue a message to release the address back to the server when the
client no longer needs the address. The client may ask for a
permanent assignment by asking for an infinite lease. Even when
assigning "permanent" addresses, a server may choose to give out
lengthy but non-infinite leases to allow detection of the fact that
the client has been retired.



--
Regards,
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT,
MVP Microsoft MVP - Directory Services
Microsoft Certified Trainer

For urgent issues, you may want to contact Microsoft PSS directly. Please
check http://support.microsoft.com for regional support phone numbers.

Infinite Diversities in Infinite Combinations

 

Most likely both BOOTP and DHCP are enabled on the server, try turning off BOOTP either on the client or the server or both.

BOOTP was the predecessor of DHCP. DHCP is based on the BOOTP protocol. They both use UDP ports 67 and 68.

BOOTP does not have the concept of a lease and therefore the DHCP server can't give it one, so the DHCP server uses the BOOTP protocol to respond and therefore behaves as a BOOTP server, merely allocating an IP to a MAC; and with no lease concept, then it cannot expire the allocation and therefore shows it as infinite.

You may be able to turn off the BOOTP option on the client so that it is forced to use DHCP, but this will require manual intervention for each client as you add them to the network.

An alternative may be to disable BOOTP on the server side so that it refuses all BOOTP requests and forces the client to try any other IP allocation methods it may have, namely DHCP if it is (most likely) on.

Leonard McCoy

 

Try to turn off BOOTP...