In a routing table, the 0.0.0.0 address is a special address that represents the default route. It is used to route traffic to a specific network or subnet when no other route is available.
When a packet is sent from a host, the host looks up the destination address in its routing table to determine the next hop for the packet. If the destination address is not found in the routing table, the host will use the default route to route the packet to the next hop.
The 0.0.0.0 address is often used as the destination address in the default route because it represents the "unspecified" address, which matches any IP address. This allows the default route to be used for any destination that is not explicitly listed in the routing table.
The default route is usually set by the system administrator or network administrator, and it is often used to route traffic to the default gateway, which is the device that connects the host to the rest of the network.
In summary, the 0.0.0.0 address in the routing table represents the default route, which is used to route traffic to a specific network or subnet when no other route is available.