Let's keep refreshing our minds with IP addresses. In real world applications, some special IP addresses are used. Table 1 shows the ranges and description of these IP addresses.
Net ID | Subnet ID | Host ID | Used as Source Address | Used as Destination Address | Description |
All 0s | - | All 0s | Ok | Never | Applies to hosts on a network. |
All 0s | - | Host ID | Ok | Never | Applies to a specified host on a network. |
127 | - | Any value | Ok | Ok | Used as a loopback address. |
All 1s | - | All 1s | Never | Ok | Applies to restricted broadcast (never forwarded). |
net-id | - | All 1s | Never | Ok | Used to send broadcast packets to the network specified by the net-id. |
net-id | subnet-id | All 1s | Never | Ok | This type of addresses is used to send broadcast packets to the subnets specified by the net-id and subnet-id. |
net-id | All 1s | All 1s | Never | Ok | Used to send broadcast packets to all subnets specified by the net-id. |
In Table 1, net-id and subnet-id indicate the fields that are neither all zero bits nor all one bits.
