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Asked: 2016-07-16 15:41:01 +0800 CST

DHCP leases file has 200+ instances of the same lease?

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I'm not sure what's going on here. I have a CentOS 7 DHCP server, and the leases file is growing at a linear but steady rate - it's re-issuing the same lease to the same MAC over and over again, and adding the new stanza to the file.

This server serves DHCP for a network of roughly 300 systems.

The DHCP config file looks like this:

ddns-update-style interim;

allow booting;
allow bootp;

ignore client-updates;
set vendorclass = option vendor-class-identifier;
one-lease-per-client true;
option pxe-system-type code 93 = unsigned integer 16;
DHCPDARGS="enp130s0f0";

subnet 10.101.24.0 netmask 255.255.252.0 {
     option routers             10.101.24.1;
     option domain-name-servers 10.101.6.62;
     option domain-search "foo.com";
     option subnet-mask         255.255.252.0;
     range dynamic-bootp        10.101.24.31 10.101.27.254;
     default-lease-time         172800;
     max-lease-time             172800;
     next-server                10.101.24.21;
     class "pxeclients" {
          match if substring (option vendor-class-identifier, 0, 9) = "PXEClient";
          if option pxe-system-type = 00:02 {
                  filename "ia64/elilo.efi";
          } else if option pxe-system-type = 00:06 {
                  filename "grub/grub-x86.efi";
          } else if option pxe-system-type = 00:07 {
                  filename "grub/grub-x86_64.efi";
          } else {
                  filename "pxelinux.0";
          }
     }
}

Is it normal behavior for dhcpd to reply to a request for a lease from the same MAC over and over and add its stanza to the end of the dhcpd.leases file, again, over and over?

Is there some setting I'm missing?

centos7 dhcp-server dhcpd

1 Answers

  1. quoting man 5 dhcpd.leases:

    The Internet Systems Consortium DHCP Server keeps a persistent database of leases that it has assigned. This database is a free-form ASCII file containing a series of lease declarations. Every time a lease is acquired, renewed or released, its new value is recorded at the end of the lease file. So if more than one declaration appears for a given lease, the last one in the file is the current one.

    Normal behaviour, do not worry.

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