[Free] 2019(Nov) EnsurePass Cisco 100-105 Dumps with VCE and PDF 71-80

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Question No.71

Refer to the exhibit. Assume that all router interfaces are operational and correctly configured. In addition, assume that OSPF has been correctly configured on router R2. How will the default route configured on R1 affect the operation of R2?


  1. Any packet destined for a network that is not directly connected to router R2 will be dropped immediately.

  2. Any packet destined for a network that is not referenced in the routing table of router R2 will be directed to R1. R1 will then send that packet back to R2 and a routing loop will occur.

  3. Any packet destined for a network that is not directly connected to router R1 will be dropped.

  4. The networks directly connected to router R2 will not be able to communicate with the,, and subnetworks.

  5. Any packet destined for a network that is not directly connected to router R2 will be dropped immediately because of the lack of a gateway on R1.

    Correct Answer: B


    First, notice that the more-specific routes will always be favored over less-specific routes regardless of the administrative distance set for a protocol. In this case, because we use OSPF for three networks (,, so

    the packets destined for these networks will not be affected by the default route.

    The default route configured on R1 quot;ip route serial0/0 will send any packet whose destination network is not referenced in the routing table of router R1 to R2, it doesn#39;t drop anything. These routes are declared in R1 and the question says that quot;OSPF has been correctly configured on router R2, so network directly connected to router R2 can communicate with those three subnetworks.

    As said above, the default route configured on R1 will send any packet destined for a network that is not referenced in its routing table to R2; R2 in turn sends it to R1 because it is the only way and a routing loop will occur.

    Question No.72

    Refer to the exhibit. Which two statements are true about the loopback address that is configured on RouterB? (Choose two.)


    1. It ensures that data will be forwarded by RouterB.

    2. It provides stability for the OSPF process on RouterB.

    3. It specifies that the router ID for RouterB should be

    4. It decreases the metric for routes that are advertised from RouterB.

    5. It indicates that RouterB should be elected the DR for the LAN.

Correct Answer: BC


A loopback interface never comes down even if the link is broken so it provides stability for the OSPF process (for example we use that loopback interface as the router-id) The router-ID is chosen in the order below:

The highest IP address assigned to a loopback (logical) interface.

If a loopback interface is not defined, the highest IP address of all active router#39;s physical interfaces will be chosen. gt; The loopback interface will be chosen as the router ID of RouterB.

Question No.73

Given an IP address of, what is the subnet address?






Correct Answer: C


248 mask uses 5 bits (1111 1000)

42 IP in binary is (0010 1010)

The base subnet therefore is the lowest binary value that can be written without changing the output of an AND operation of the subnet mask and IP…

1111 1000 AND

0010 1010 equals

0010 1000 – which is .40

/24 is standard class C mask.

Adding the 5 bits from the .248 mask gives /29

Question No.74

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

  1. All OSPF routers in an area must have the same process ID.

  2. Only one process number can be used on the same router.

  3. Different process identifiers can be used to run multiple OSPF processes

  4. The process number can be any number from 1 to 65,535.

  5. Hello packets are sent to each neighbor to determine the processor identifier.

Correct Answer: CD


Multiple OSPF processes can be configured on a router using multiple process ID#39;s. The valid process ID#39;s are shown below:

Edge-B(config)#router ospf

lt;1-65535gt; Process ID

Question No.75

What is the default administrative distance of the OSPF routing protocol?













Correct Answer: C


Default Distance Value Table

This table lists the administrative distance default values of the protocols that Cisco supports:


If the administrative distance is 255, the router does not believe the source of that route and does not install the route in the routing table.

Question No.76

What OSPF command, when configured, will include all interfaces into area 0?

A. network area 0

B. network area 0

C. network area 0

D. network all-interfaces area 0

Correct Answer: A


Example 3-1 displays OSPF with a process ID of 1 and places all interfaces configured with an IP address in area 0. The network command network area 0 dictates that you do not care ( what the IP address is, but if an IP address is enabled on any interface, place it in area 0.

Example 3-1 Configuring OSPF in a Single Area

router ospf 1

network area 0

Reference: http://www.ciscopress.com/articles/article.asp?p=26919amp;seqNum=3

Question No.77

To allow or prevent load balancing to network, which of the following commands could be used in R2? (Choose two.)


  1. R2(config-if)#clock rate

  2. R2(config-if)#bandwidth

  3. R2(config-if)#ip ospf cost

  4. R2(config-if)#ip ospf priority

  5. R2(config-router)#distance ospf

Correct Answer: BC



The cost (also called metric) of an interface in OSPF is an indication of the overhead required to send packets across a certain interface. The cost of an interface is inversely proportional to the bandwidth of that interface. A higher bandwidth indicates a lower cost. There is more overhead (higher cost) and time delays involved in crossing a 56k serial line than crossing a 10M Ethernet line. The formula used to calculate the cost is:

Cost = 10000 0000/bandwidth in bps

For example, it will cost 10 EXP8/10 EXP7 = 10 to cross a 10M Ethernet line and will cost 10 EXP8/1544000 =64 to cross a T1 line.

By default, the cost of an interface is calculated based on the bandwidth; you can force the cost of an interface with the ip ospf cost lt;valuegt; interface subconfiguration mode command.

Question No.78

Refer to the exhibit. The network is converged.After link-state advertisements are received from Router_A, what information will Router_E contain in its routing table for the subnets and


A.[110/13] via, 00:00:07, FastEthemet0/0[110/13] via, 00:00:16, FastEthemet0/0

B.[110/1] via, 00:00:07, Serial1/0[110/3] via, 00:00:16, FastEthemet0/0

C.[110/13] via, 00:00:07, Serial1/0[110/13] via, 00:00:16, Serial1/0[110/13] via, 00:00:16,


D.[110/3] via, 00:00:07, Serial1/0[110/3] via, 00:00:16, Serial1/0

Correct Answer: A


Router_E learns two subnets subnets and via Router_A through FastEthernet interface. The interface cost is calculated with the formula 108 / Bandwidth. For FastEthernet it is 108 / 100 Mbps = 108 / 100,000,000 = 1. Therefore the cost is 12 (learned from Router_A) 1 = 13 for both subnets -gt; The cost through T1 link is much higher than through T3 link (T1 cost = 108 / 1.544 Mbps = 64; T3 cost = 108 / 45 Mbps = 2) so surely OSPF will choose the path through T3 link -gt; Router_E will choose the path from Router_A through FastEthernet0/0, not Serial1/0. In fact, we can quickly eliminate answers B, C and D because they contain at least one subnet learned from Serial1/0 -gt; they are surely incorrect.

Question No.79

An administrator is in the process of changing the configuration of a router. What command will allow the administrator to check the changes that have been made prior to saving the new configuration?

  1. Router# show startup-config

  2. Router# show current-config

  3. Router# show running-config

  4. Router# show memory

  5. Router# show flash

  6. Router# show processes

Correct Answer: C


This command followed by the appropriate parameter will show the running config hence the admin will be able to see what changes have been made, and then they can be saved.

Question No.80

A network administrator is troubleshooting the OSPF configuration of routers R1 and R2. The routers cannot establish an adjacency relationship on their common Ethernet link. The graphic shows the output of the show ip ospf interface e0 command for routers R1 and R2. Based on the information in the graphic, what is the cause of this problem?


  1. The OSPF area is not configured properly.

  2. The priority on R1 should be set higher.

  3. The cost on R1 should be set higher.

  4. The hello and dead timers are not configured properly.

  5. A backup designated router needs to be added to the network.

  6. The OSPF process ID numbers must match.

Correct Answer: D


In OSPF, the hello and dead intervals must match and here we can see the hello interval is set to 5 on R1 and 10 on R2. The dead interval is also set to 20 on R1 but it is 40 on R2.

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