Reference Manual for the Model RP614 v2 Web Safe Router
Networks, Routing, and Firewall Basics B-7
The following table displays several common netmask values in both the dotted-decimal and the
masklength formats.
NETGEAR strongly recommends that you configure all hosts on a LAN segment to use the same
netmask for the following reasons:
• So that hosts recognize local IP broadcast packets.
When a device broadcasts to its segment neighbors, it uses a destination address of the local
network address with all ones for the host address. In order for t his scheme to work, a ll devi ces
on the segment must agree on which bits comprise the host address.
• So that a local router or bridge recognizes which addresses are local and which are remote.
Private IP Addresses
If your local network is isolated from the Internet (for example, when using NAT), you can assign
any IP addresses to the hosts without problems. However, the IANA has reserved the following
three blocks of IP addresses specifically for private networks:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
Table 6-2. Netmask Formats
Dotted-Decimal Masklength
255.0.0.0 /8
255.255.0.0 /16
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29
255.255.255.252 /30
255.255.255.254 /31
255.255.255.255 /32