Routing Flashcards
All routing chapters
Describe routing
When a router receives an IP packet on one interface, it determines which interface to use to forward the packet to the destination.
What are the primary functions of a router
to determine the best path to forward packets based on the info in the routing table, and to forward npackets toward their destination
The ip routing table is used like a map by the router to determine the best path for a given network?
True
The router must determine the best path in the routing table. What is the best path in the routing table called?
the “longest match”
Default static routes (0.0.0.0) are used to send packets to unknown destinations. When do we use it?
On a “border” router to the internet, and on a stub network, where there is only one exit to the rest of the network.
when in routing table, it is labeled as an S* at the top of the table and “gateway of last resort” appears. Also a stub network is good to use on dead end networks.
What is the longest match process?
A process the router uses to find a match between the destination IP address of the packet and a routing entry in the routing table
What are classful and classless protocols?
classful protocols do not carry subnet masks, while classless routing protocols do
For there to be a match between the destination IP address of a packet and a route in the routing table, what must happen?
a minimum number of far-left bits must match between the IP address of the packet and the route in the routing table. The prefix length of the route in the table is used to determine the minimum number of far-left bits that must match.
Remember, an ip packet only contains the destination ip address and not the prefix length
The route with the greatest number of equivalent far-left bits, or the longest match, is always the preferred route
True
What table does a router use to determine how to forward an IP packet?
Routing Table
What action will a router take on a packet with a destination IP address that is on a remote network
It will forward the packet to a next-hop router
Which routes may be found in a routing table?
directly connected networks, static routes, dynamic routing protocol routes, and default route
What is used to determine the minimum number of far-left bits that must match between the prefix in the route entry and the destination bits?
The prefix length in the routing table entry
What are directly connected networks?
Networks that are configured on the active interfaces of a router.
What are remote networks?
networks not directly connected to the router. Routers learn about remote networks through static routes and dynamic routing protocols. Static rotues are configured manually, while dynamic routing protocols are added when routes are learned dynamically through protocols such as OSPF
