Which statements describe the routing protocol OSPF? (Choose three.)
A. It supports VLSM.
B. It is used to route between autonomous systems.
C. It confines network instability to one area of the network.
D. It increases routing overhead on the network.
E. It allows extensive control of routing updates.
F. It is simpler to configure than RIP v2.
The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.
OSPF uses flooding to exchange link-state updates between routers. Any change in routing information is flooded to all routers in the network. Areas are introduced to put a boundary on the explosion of link-state updates. Flooding and calculation of the Dijkstra algorithm on a router is limited to changes within an area.
Refer to the exhibit. A network administrator configures a new router and enters the copy startup-config running-config command on the router. The network administrator powers down the router and sets it up at a remote location. When the router starts, it enters the system configuration dialog as shown. What is the cause of the problem?
A. The network administrator failed to save the configuration.
B. The configuration register is set to 0x2100.
C. The boot system flash command is missing from the configuration.
D. The configuration register is set to 0x2102.
E. The router is configured with the boot system startup command.
The “System Configuration Dialog” appears only when no startup configuration file is found. The network administrator has made a mistake because the command “copy startup-config running- config” will copy the startup config (which is empty) over the running config (which is configured by the administrator). So everything configured was deleted. Note: We can tell the router to ignore the start-up configuration on the next reload by setting the register to 0?142. This will make the “System Configuration Dialog” appear at the next reload.
What is the default administrative distance of OSPF?
Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.
Default Distance Value Table
This table lists the administrative distance default values of the protocols that Cisco supports:
Default Distance Values
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol (BGP)
Intermediate System-to-Intermediate System (IS-IS)
Routing Information Protocol (RIP)
Exterior Gateway Protocol (EGP)
On Demand Routing (ODR)
Which characteristics are representative of a link-state routing protocol? (Choose three.)
A. provides common view of entire topology
B. exchanges routing tables with neighbors
C. calculates shortest path
D. utilizes event-triggered updates
E. utilizes frequent periodic updates
Each of routers running link-state routing protocol learns paths to all the destinations in its “area” so we can say although it is a bit unclear.
Link-state routing protocols generate routing updates only (not the whole routing table) when a change occurs in the network topology so
Link-state routing protocol like OSPF uses Dijkstra algorithm to calculate the shortest path -> . Unlike Distance vector routing protocol (which utilizes frequent periodic updates), link-state routing protocol utilizes event-triggered updates (only sends update when a change occurs) ->
Which command would you configure globally on a Cisco router that would allow you to view directly connected Cisco devices?
A. enable cdp
B. cdp enable
C. cdp run
D. run cdp
CDP is enabled on Cisco routers by default. If you prefer not to use the CDP capability, disable it with the no cdp run command. In order to reenable CDP, use the cdp run command in global configuration mode. The “cdp enable” command is an interface command, not global.
Which two locations can be configured as a source for the IOS image in the boot system command? (Choose two.)
C. flash memory
D. HTTP server
E. TFTP server
F. Telnet server
The following locations can be configured as a source for the IOS image:
1. + Flash (the default location)
2. + TFTP server
3. + ROM (used if no other source is found)
Which two statements describe the process identifier that is used in the command to configure OSPF on a router? (Choose two.)
Router(config)# router ospf 1
A. All OSPF routers in an area must have the same process ID
B. Only one process number can be used on the same router.
C. Different process identifiers can be used to run multiple OSPF processes
D. The process number can be any number from 1 to 65,535.
E. Hello packets are sent to each neighbor to determine the processor identifier.
Multiple OSPF processes can be configured on a router using multiple process ID’s.
The valid process ID’s are shown below:
Edge-B(config)#router ospf ?
<1-65535> Process ID
Which three elements must be used when you configure a router interface for VLAN trunking? (Choose three.)
A. one physical interface for each subinterface
B. one IP network or subnetwork for each subinterface
C. a management domain for each subinterface
D. subinterface encapsulation identifiers that match VLAN tags
E. one subinterface per VLAN
F. subinterface numbering that matches VLAN tags
This scenario is commonly called a router on a stick. A short, well written article on this operation can be found here:
Which commands are required to properly configure a router to run OSPF and to add network 192.168.16.0/24 to OSPF area 0? (Choose two.)
A. Router(config)# router ospf 0
B. Router(config)# router ospf 1
C. Router(config)# router ospf area 0
D. Router(config-router)# network 192.168.16.0 0.0.0.255 0
E. Router(config-router)# network 192.168.16.0 0.0.0.255 area 0
F. Router(config-router)# network 192.168.16.0 255.255.255.0 area 0
In the router ospf
command, the ranges from 1 to 65535 so o is an invalid number -> but To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assgin an area to this process -> .
A router receives information about network 192.168.10.0/24 from multiple sources. What will the router consider the most reliable information about the path to that network?
A. a directly connected interface with an address of 192.168.10.254/24
B. a static route to network 192.168.10.0/24
C. a RIP update for network 192.168.10.0/24
D. an OSPF update for network 192.168.0.0/16
E. a default route with a next hop address of 192.168.10.1
F. a static route to network 192.168.10.0/24 with a local serial interface configured as the next hop
When there is more than one way to reach a destination, it will choose the best one based on a couple of things. First, it will choose the route that has the longest match; meaning the most specific route. So, in this case the /24 routes will be chosen over the /16 routes. Next, from all the /24 routes it will choose the one with the lowest administrative distance. Directly connected routes have an AD of 1 so this will be the route chosen.
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