What does the following message in /var/log/messages logfile meen?

Dec 11 11:12:54 SWA-FS1 dhcpd: DHCPINFORM from 10.112.24.126 via eth0:
not authoritative for subnet 10.112.24.0
Dec 11 11:12:54 SWA-FS1 dhcpd: If this DHCP server is authoritative
for that subnet,
Dec 11 11:12:54 SWA-FS1 dhcpd: please write an `authoritative;'
directive either in the
Dec 11 11:12:54 SWA-FS1 dhcpd: subnet declaration or in some scope
that encloses the
Dec 11 11:12:54 SWA-FS1 dhcpd: subnet declaration - for example, write
it at the top
Dec 11 11:12:54 SWA-FS1 dhcpd: of the dhcpd.conf file.

the first line is there from multiple clients, almost all the time
and the last 5 lines are in the file every 3 minutes.

our dhcpd.conf file:

option domain-name "assen.swa";
option domain-name-servers 10.112.24.6, 10.112.24.7;
option routers 10.112.24.1;
option ntp-servers 10.112.24.6;
option slp-directory-agent false 10.112.24.6, 10.112.24.7;
option vendor-class-identifier "PXEClient";
option wpad-url code 252 = text;
option wpad-url "http://10.112.24.6/proxy.pac\n";
ddns-update-style none;
default-lease-time 259200;
subnet 10.112.24.0 netmask 255.255.255.0 {
range 10.112.24.30 10.112.24.199;
default-lease-time 518400;
}