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Appendix 4
Dissecting the Windows Routing Table
C:\>ipconfig
Windows IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 172.16.0.2
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 172.16.0.1
C:\>route print or netstat –r
===========================================================================
Network Destination Netmask Gateway Interface Metric
1 0.0.0.0 0.0.0.0 172.16.0.1 172.16.0.2 1
2 127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
3 172.16.0.0 255.255.255.0 172.16.0.2 172.16.0.2 20
4 172.16.0.2 255.255.255.255 127.0.0.1 127.0.0.1 20
5 172.16.255.255 255.255.255.255 172.16.0.2 172.16.0.2 20
6 224.0.0.0 240.0.0.0 172.16.0.2 172.16.0.2 20
7 255.255.255.255 255.255.255.255 172.16.0.2 172.16.0.2 1
Default Gateway: 172.16.0.1
===========================================================================
- Gateway is the IP address of the next-hop router inbound interface.
Interface is the IP address of the local router outbound interface.
Metric is the distance to a remote (or destination) network. If there are multiple routes to a same
network, the route with the lowest metric will be used to forward packets to the network.
- Generally, gateway and interface reside in the same subnet.
- Below describes all the routes displayed in the routing table above:
1) Default route or default gateway.
2) Loopback network – destine all packets to the 127.0.0.0/8 network to itself (127.0.0.1).
3) Route to local network – the directly attached network.
4) Route to local host (127.0.0.1), which is identified as a host route.
5) Route to directed broadcast, the broadcast which is sent to all hosts of a particular subnet or
a group of subnets. It is identified as a host route. May be forwarded by a router (normally
the default gateway) configured with the ip directed-broadcast interface subcommand.
6) Route to multicast networks.
7) Route to flooded / limited broadcast, the local broadcast within a subnet. It is identified as a
host route. Normally sent by hosts that do not know their network numbers and addresses and
are querying some servers for those information (eg: DHCP). May be forwarded by routers
with the ip helper-address {ip-addr} interface subcommand.
Note: Host routes are destinations with the subnet mask of 255.255.255.255.
- Below shows the command syntax for adding a [persistent] route:
route [-p] add {dest-net-addr} mask {netmask} {gw-ip-addr} [metric {metric}]
- Below shows the command syntax for deleting or removing an existing [persistent] route:
route delete {dest-net-addr} [mask {netmask} [gw-ip-addr]]
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Copyright © 2008 Yap Chin Hoong
yapchinhoong@hotmail.com