DHCPd sending lease expiration of 3600 seconds

David Sherman dsherman at bluecatnetworks.com
Wed Feb 18 00:28:04 UTC 2009

You are getting MCLT time. It is normal behavior for DHCP Failover configuration. After 50% of lease time, client will request Renew and will get configured lease time.
You will get MCLT time every time you perform release/renew or booting up your computer

----- Original Message -----
From: dhcp-users-bounces at lists.isc.org <dhcp-users-bounces at lists.isc.org>
To: dhcp-users at lists.isc.org <dhcp-users at lists.isc.org>
Sent: Tue Feb 17 18:46:58 2009
Subject: DHCPd sending lease expiration of 3600 seconds

On my CentOS 5.2 system I am setting up some network services for our
corporate environment. DHCP works great EXCEPT that clients are getting
a lease from the server that expires in 3600 second even though the
config says otherwise. Here is my config:

# server is authoritative

# allow for booting over the network
#allow booting;

# allow for booting
#allow bootp;

# TFTP server for booting

# kernel for network booting
#filename "pxelinux.0";

# setup dynamic DNS updates
ddns-update-style interim;
ddns-updates on;
ddns-domainname "x10.com";

# lease expiration
default-lease-time 86400;
max-lease-time 86400;

# control client behaviour
allow unknown-clients;
ignore client-updates;

key rndckey {
	algorithm	hmac-md5;

	# get from the /etc/rndc.key file
	secret		"R7+OZq87s/+0MiP+g2Mf0w==";

# forward zone to update
zone x10.com
	key rndckey;

# reverse zone to update
zone 11.168.192.in-addr.arpa
	key rndckey;

# fail over configuration
failover peer "x10-corp" {
	# This is the primary

	# primarys ip address
	port 647;
	# peer's ip address
	peer address;
	peer port 647;

	max-response-delay 60;
	max-unacked-updates 10;
	mclt 3600;
	split 128;
	load balance max seconds 3;

# zone to issue addresses from
subnet netmask
	# pool for dhcp leases
	pool {
		failover peer "x10-corp";
		deny dynamic bootp clients;         
		option routers;
		option domain-name "x10.com";
		option domain-name-servers,;
		option netbios-name-servers;
		option netbios-dd-server;
		option netbios-node-type 8;
		option subnet-mask;

		host jay-clark-xp {
			hardware ethernet 00:17:31:89:03:fa;

I can see clearly in a WireShark network trace that the server responds back with the lease marked as expiring in 1 hour. It's like the service is ignoring the default-lease and max-lease settings. Any thoughts?

Geoff Sweet

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