IPv4 Private Address Space

[Louis Garcia]

According to standards set forth in Internet Engineering Task Force
(IETF) document RFC-1918, the following IPv4 address ranges are
reserved by the IANA for private internets,

10.0.0.0/8 IP addresses: 10.0.0.0 – 10.255.255.255
172.16.0.0/12 IP addresses: 172.16.0.0 – 172.31.255.255
192.168.0.0/16 IP addresses: 192.168.0.0 – 192.168.255.255

dhcpd does not seem to like subnet/mask combination.

          authoritative;
          default-lease-time 600;
          max-lease-time 7200;
          subnet 172.16.4.0 netmask 255.240.0.0 {
                      option domain-name-servers 172.16.4.1;
                      option broadcast-address 172.31.255.255;
                      option routers 172.16.4.1;
                      option ntp-servers 172.16.4.1;
                      range 172.16.4.50 172.16.4.254;
          }

May 11 16:07:01 dhcpd[4540]: Internet Systems Consortium DHCP Server 4.4.2b1
May 11 16:07:01 dhcpd[4540]: Copyright 2004-2019 Internet Systems Consortium.
May 11 16:07:01 dhcpd[4540]: All rights reserved.
May 11 16:07:01 dhcpd[4540]: For info, please visit
https://www.isc.org/software/dhcp/
May 11 16:07:01 dhcpd[4540]: /etc/dhcp/dhcpd.conf line 4: subnet
172.16.4.0 netmask 255.240.0.0: bad subnet number/mask combination.
May 11 16:07:01 dhcpd[4540]: subnet 172.16.4.0 netmask 255.240.0.0
May 11 16:07:01 dhcpd[4540]:
                    ^
May 11 16:07:01 dhcpd[4540]: Configuration file errors encountered -- exiting
May 11 16:07:01 dhcpd[4540]:
May 11 16:07:01 dhcpd[4540]: This version of ISC DHCP is based on the
release available
May 11 16:07:01 dhcpd[4540]: on ftp.isc.org. Features have been added
and other changes
May 11 16:07:01 dhcpd[4540]: have been made to the base software
release in order to make
May 11 16:07:01 dhcpd[4540]: it work better with this distribution.
May 11 16:07:01 dhcpd[4540]:
May 11 16:07:01 dhcpd[4540]: Please report issues with this software via:
May 11 16:07:01 dhcpd[4540]: https://bugzilla.redhat.com/
May 11 16:07:01 dhcpd[4540]:
May 11 16:07:01 dhcpd[4540]: exiting.
May 11 16:07:01 dhcpd.service: Main process exited, code=exited,
status=1/FAILURE