What is a Routing Table in a Computer Network?

Each router on the network supports a routing table in memory that may be simple or complex. In the simplest form, the table consists of pairs of IP addresses.

When the originating station involves that the intended destination is directly reachable, the frame is sent immediately to the frame's destination IP address. In such a situation, a unique address occurs in the routing table known as Default Gateway Address.

The routing decisions depend on the following points:

  • The destination IP address and router IP are concealed to decide if the incoming packet Notes is to be forwarded to another network or not. If the results are equal, a packet is for a similar subnet as the destination. The frame is then delivered immediately to the data link address of the destination.
  • When the result is not the same, it indicates that the destination is not on the same subnet. The routing table is tested to determine if the exact, complete, 32-bit destination address is specified, referred to as a host-specific routing. If the hostspecific route is selected, the frame is transmitted to the IP destination denoted in the table that indicates that this destination is the next router in line with the method to the destination.
  • When the host-specific route is not found in the routing table, then the masked address is used to look up the key in the routing table to examine whether the network/subnetwork is specified. If specified, the frame is sent to the IP address specified in the table that implies that this is the next router's IP address in line.
  • When both conditions 2 and 3 given above fail, the frame is forwarded to the address specified as the target for the Default Gateway.
  • When no default gateway is specified, it is assumed that all unknown destinations are directly reachable. The destination IP station's physical address is resolved, and the frame is forwarded directly to the destination. This is sometimes called activating Proxy ARP.