When this flag is missing, it means the destination is in the same network (direct delivery).

This field defines the address of the next router to which the packet is delivered.

This indicates that the routing information for this destination has been modified by a redirection message from ICMP.

If this is not present, it means that the router is down. The packet cannot be forwarded and is discarded.

This indicates that routing information for this destination has been added to the host routing table by a redirection message from ICMP

This field gives the number of users of a specific route at a specific time.

This field will be applied to every packet that arrives to a host/router

When it is missing, it means that the address is only the network address of the destination.

This field defines the address of the destination host in the case of host-specific routing.