Linux DHCP Server

Errors

interface name too long

dhcpd -t
or
dhcpd -t <file and location>

Example using file names:
dhcpd -t /etc/dhcp/dhcpd.conf

/etc/dhcp/dhcpd.conf: interface name too long (is 20)

dhcpd -t /etc/default/isc-dhcp-server

/etc/default/isc-dhcp-server: interface name too long (is 28)

tail -f /var/log/message

Mar 14 19:50:49 server dhcpd: No subnet declaration for eth1 (172.16.31.254).
Mar 14 19:50:49 server dhcpd: ** Ignoring requests on eth1.  If this is not what
Mar 14 19:50:49 server dhcpd:    you want, please write a subnet declaration
Mar 14 19:50:49 server dhcpd:    in your dhcpd.conf file for the network segment
Mar 14 19:50:49 server dhcpd:    to which interface eth1 is attached. **
Mar 14 19:50:49 server dhcpd: 
Mar 14 19:50:49 server dhcpd: 
Mar 14 19:50:49 server dhcpd: Not configured to listen on any interfaces!

cat /etc/network/interfaces

~
# To Router Interface
auto eth1
iface eth1 inet static
       address 172.16.31.254
       netmask 255.255.255.0
       network 172.16.31.0
       broadcast 172.16.31.255

This is because the interface set for DHCP does have the subnet defined in a declaration statement in dhcp.conf.

At the very least declare the subnet even if you do not plan on serving DHCP to that particular subnet.

subnet 172.16.31.0 netmask 255.255.255.0 {
}