Contents of an IP Routing Table
The following are the fields of a typical IP routing table entry:
• | Destination The destination can be either an IP address or a class-based, subnetted, or supernetted network ID. In the Windows 2000 IP routing table, this column is named Network Destination. |
• | Network Mask The bit mask that is used to match a destination IP address to the value in the Destination field. In the Windows 2000 IP routing table, this column is named Netmask. |
• | Next-Hop The IP address to which the packet is forwarded. In the Windows 2000 IP routing table, this column is named Gateway. |
• | Interface The network interface that is used to forward the IP packet. |
• | Metric A number used to indicate the cost of the route so that the best route, among potentially multiple routes to the same destination, can be selected. A common use of the metric is to indicate the number of hops (the number of links or routers to cross) en route to the destination. |
Routing table entries can be used to store the following types of routes:
• | Directly-attached network routes Routes for subnets to which the node is directly attached. For directly-attached network routes, the Next-Hop field can either be blank or contain the IP address of the interface on that subnet. |
• | Remote network routes Routes for subnets that are available across routers and are not directly attached to the node. For remote network routes, the Next-Hop field is the IP address of a local router. |
• | Host routes A route to a specific IP address. Host routes allow routing to occur on a per-IP address basis. For host routes, the network ID is a specific IP address and the network mask is 255.255.255.255. |
• | Default route The default route is used when a more specific network or host route is not found. The default route destination is 0.0.0.0 with the network mask of 0.0.0.0. The next-hop address of the default route is typically the default gateway of the node. |