Default Route

A default route of a computer that is participating in computer networking is the packet forwarding rule (route) taking effect when no other route can be determined for a given Internet Protocol (IP) destination address. All packets for destinations not established in the routing table are sent via the default route. This route generally points to another router, which treats the packet the same way: If a route matches, the packet is forwarded accordingly, otherwise the packet is forwarded to the default route of that router. The process repeats until a packet is delivered to the destination. Each router traversal counts as one hop in the distance calculation for the transmission path.

The route evaluation process in each router uses the longest prefix match method to obtain the most specific route. The network with the longest subnet mask that matches the destination IP address is the next-hop network gateway.

The default route in Internet Protocol Version 4 (IPv4) is designated as the zero-address in CIDR notation, often called the quad-zero route. The subnet mask is given as /0, which effectively specifies all networks, and is the shortest match possible. A route lookup that does not match any other route, falls back to this route. Similarly, in IPv6, the default route is specified by ::/0.

In the highest-level segment of a network, administrators generally point the default route for a given host towards the router that has a connection to a network service provider. Therefore, packets with destinations outside the organization's local area network, typically destinations on the Internet or a wide area network, are forwarded to the router with the connection to that provider.

The device to which the default route points is often called the default gateway, and it often carries out other functions such as packet filtering, firewalling, or proxy server operations.

Other articles related to "default, default route, route, routes":

Default Gateway - Example2
... Hosts and addresses PC1, default gateway PC2, default gateway PC3, default gateway Router1 ... (examples may vary) Cost (decreases the TTL) (default route) Assigned by ISP (i.e ... may vary) Cost (decreases the TTL) (default route) eth0 (Ethernet 1st adapter) 10 eth1 (Ethernet 2nd adapter) 10 Router3 Network ID ...
Stub Network
... out via a single path, with the network aware only of a default route to non-local destinations ... to the corporate network by only one router, or multiple default routers connected to the same logical upstream destination ... The routers will only route packets into the LAN if it's destined for the LAN, and out from the LAN if it originated on the LAN ...
Open Shortest Path First - Area Types - Stub Area - Proprietary Extensions
... However, this area does not allow summary routes in addition to not having external routes, that is, inter-area (IA) routes are not summarized into totally stubby areas ... The only way for traffic to get routed outside of the area is a default route which is the only Type-3 LSA advertised into the area ... When there is only one route out of the area, fewer routing decisions have to be made by the route processor, which lowers system resource utilization ...

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