Section 5. Routing Flashcards
Q1-Provide a brief description of routing.
Routing is the process of finding a path to a destination and moving information across an internetwork from the source to the destination.
Q2-What are the two key functions that a router performs?
The two key functions that a router performs are path determination (routing) and packet forwarding (switching). Routing protocols used by the routing process are responsible for learning and maintaining awareness of the network topology. The switching function is the process of moving packets from an inbound interface to an outbound interface.
Q3-How does a router determine the path a packet should take to reach its destination?
A router determines a path a packet should take to reach a destination by picking the best path to the destination. The best path a packet should take is determined by one of the following methods:
Static routing
Dynamic routing
Default routing
Q4-What are the three packet-forwarding mechanisms supported by Cisco routers?
The three packet-forwarding mechanisms supported by Cisco routers are
Process switching
Fast switching
Cisco Express Forwarding
Q5-Define processing switching.
Processing switching is the oldest forwarding mechanism supported on Cisco routers. Every packet processed by the router requires a full lookup in the routing table.
Q6-What is fast switching?
Fast switching is a process that uses the cache to speed routing. When a packet is received for a destination, the first packet is process switched and an entry is created in the router’s cache. Subsequent packets are switched in the interrupt code using the cache to improve performance.
Q7-Define Cisco Express Forwarding.
Cisco Express Forwarding (CEF) is the preferred Cisco IOS packet-forwarding mechanism. CEF consists of two key components: the Forwarding Information Base (FIB) and adjacencies. The FIB is similar to the routing table created by the router but maintains only the next-hop address for a particular route. The adjacency table maintains Layer 2 information linked to a particular FIB entry, avoiding the need to do an ARP request for each table lookup.
Q8-What is the difference between a routed and a routing protocol?
A routed protocol is a protocol that provides the information in its network layer to allow a packet to direct traffic and defines the use of fields within a packet. Examples of routed protocols are IPv4 and IPv6.
A routing protocol finds routes in an internetwork and maintains route awareness. Routing protocols aid in building and maintaining routing tables that routers will use to determine how routed protocols are routed. Routing Information Protocol v2 (RIPv2), Enhanced IGRP (EIGRP), Intermediate System–to–Intermediate System (IS-IS), Open Shortest Path First (OSPF), and Border Gateway Protocol (BGP) are examples of routing protocols.
Q9-What are six types of information stored in routing tables?
The following are six types of information stored in routing tables:
Destination network address
Next-hop address
Exiting interface
Metric
Administrative distance
Routing source
Q10-How do routing protocols maintain their routing tables with each other?
Routing protocols maintain their routing tables through the transmission of messages. These messages are exchanged between routers at periodic intervals or when a change in the network topology occurs. The information contained in the messages varies from routing protocol to routing protocol.
Q11-What are the four types of routes found in a routing table?
The four types of routes found in a routing table are as follows:
Directly connected networks: Route entries that a router is directly connected to.
Static routes: Routes entered manually by an administrator.
Dynamic routes: Routes learned and populated by a routing protocol.
Default route: Used to route packets when the router does not have a specific destination for packets in its routing table. The default route is entered manually or dynamically.
Q12-When a router is powered on, what three tasks does the router perform?
The router performs the following tasks when powered on:
- Runs a power-on self-test (POST) to test the hardware
- Finds and loads the IOS
- Finds and applies the router configuration file, if one exists
Q13-Upon first boot, a new router does not have a configuration file to load. In the event that a router has no configuration file, what happens?
If a router does not find a configuration file, the router runs setup mode, a question-driven configuration process that allows you to configure basic router parameters.
Q14-On a Cisco router, how do you display the configuration running in RAM?
You display the configuration running in RAM using the show running-config privileged mode command.
Q15-On a Cisco router, how do you view the configuration stored in nonvolatile RAM (NVRAM)?
You view the configuration stored in NVRAM using the show startup-config privileged mode command.
Q16-How do you store the active configuration of a Cisco router to NVRAM?
To save the running config to the startup config, use the copy running-config startup-config privileged mode command.
Q17-How do you give a Cisco router a name?
The hostname name global configuration command configures a name on a Cisco router.
For example, the following command changes the router’s host name to RouterA:
Router(config)# hostname RouterA
RouterA(config)#
Q18-What is the correct command to add the description “Link to West LA” to an interface on a Cisco router?
A. name Link to West LA
B. interface description Link to West LA
C. description Link to West LA
D. interface name Link to West LA
C. The command to add a description to an interface is the description interface-description interface configuration command.