[2021-New] Cisco 100-105 Dumps With Update Exam Questions (121-130)

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100-105 Exam Questions - Online Test

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Q1. - (Topic 3)

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?

A. The OSPF area is not configured properly.

B. The priority on R1 should be set higher.

C. The cost on R1 should be set higher.

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

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

F. The OSPF process ID numbers must match.

Answer: D

Explanation:

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.

Q2. - (Topic 7)

When a router makes a routing decision for a packet that is received from one network and destined to another, which portion of the packet does if replace?

A. Layer 2 frame header and trailer

B. Layer 3 IP address

C. Layer 5 session

D. Layer 4 protocol

Answer: A

Explanation:

Router Switching Function (1.2.1.1)A primary function of a router is to forward packets toward their destination. This is accomplished by using a switching function, which is the process used by a router to accept a packet on one interface and forward it out of another interface. A key responsibility of the switching function is to encapsulate packets in the appropriate data link frame type for the outgoing data link. NOTE In this context, the term “switching” literally means moving packets from source to destination and should not be confused with the function of a Layer 2 switch. After the router has determined the exit interface using the path determination function, the router must encapsulate the packet into the data link frame of the outgoing interface. What does a router do with a packet received from one network and destined for another network? The router performs the following three major steps:

. Step 1. De-encapsulates the Layer 3 packet by removing the Layer 2 frame header and trailer. . Step 2. Examines the destination IP address of the IP packet to find the best path in the routing table. . Step 3. If the router finds a path to the destination, it encapsulates the Layer 3 packet into a new Layer 2 frame and forwards the frame out the exit interface.

Q3. - (Topic 7)

On which type of device is every port in the same collision domain?

A. a router B. a Layer 2 switch

C. a hub

Answer: C

Explanation: Collision domainA collision domain is, as the name implies, a part of a network where packet collisions can occur. A collision occurs when two devices send a packet at the same time on the shared network segment. The packets collide and both devices must send the packets again, which reduces network efficiency. Collisions are often in a hub environment, because each port on a hub is in the same collision domain. By contrast, each port on a bridge, a switch or a router is in a separate collision domain.

Q4. - (Topic 3)

Scenario

Refer to the topology. Your company has decided to connect the main office with three other remote branch offices using point-to-point serial links.

You are required to troubleshoot and resolve OSPF neighbor adjacency issues between the main office and the routers located in the remote branch offices.

An OSPF neighbor adjacency is not formed between R3 in the main office and R6 in the Branch3 office. What is causing the problem?

A. There is an area ID mismatch.

B. There is a PPP authentication issue; the username is not configured on R3 and R6.

C. There is an OSPF hello and dead interval mismatch.

D. The R3 router ID is configured on R6.

Answer: D

Explanation:

Using the show running-config command we see that R6 has been incorrectly configured with the same router ID as R3 under the router OSPF process.

Q5. - (Topic 7)

Which function enables an administrator to route multiple VLANs on a router?

A. IEEE 802 1X

B. HSRP

C. port channel

D. router on a stick

Answer: D

Q6. - (Topic 3)

A network administrator is trying to add a new router into an established OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. Given the information in the partial configuration shown below, what configuration error is causing this problem?

Router(config)# router ospf 1

Router(config-router)# network 10.0.0.0 255.0.0.0 area 0

A. The process id is configured improperly.

B. The OSPF area is configured improperly.

C. The network wildcard mask is configured improperly.

D. The network number is configured improperly.

E. The AS is configured improperly.

F. The network subnet mask is configured improperly.

Answer: C

Explanation:

When configuring OSPF, the mask used for the network statement is a wildcard mask similar to an access list. In this specific example, the correct syntax would have been “network 10.0.0.0 0.0.0.255 area 0.”

Q7. - (Topic 3)

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.

Answer: C,D

Explanation:

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

Q8. - (Topic 7)

Which routing protocol has the smallest default administrative distance?

A. IBGP

B. OSPF

C. IS-IS

D. EIGRP

E. RIP

Answer: D

Explanation: http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/15986-admin-distance.html Default Distance Value TableThis table lists the administrative distance default values of the protocols that Cisco supports:

Route Source Default Distance Values

Connected interface 0 Static route 1 Enhanced Interior Gateway Routing Protocol (EIGRP) summary route 5 External Border Gateway Protocol (BGP) 20 Internal EIGRP 90 IGRP 100 OSPF 110 Intermediate System-to-Intermediate System (IS-IS) 115 Routing Information Protocol (RIP) 120 Exterior Gateway Protocol (EGP) 140 On Demand Routing (ODR) 160 External EIGRP 170 Internal BGP 200 Unknown*

Q9. - (Topic 7)

Which entity assigns IPv6 addresses to end users?

A. ICANN

B. APNIC

C. RIR

D. ISPs

Answer: C

Q10. - (Topic 5)

A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

A. decrease the window size

B. use a different source port for the session

C. decrease the sequence number

D. obtain a new IP address from the DHCP server

E. start a new session using UDP

Answer: A Explanation:

The Window bit in the header determines the number of segments that can be sent at a time. This is done to avoid overwhelming the destination. At the start of the session the window in small but it increases over time. The destination host can also decrease the window to slow down the flow. Hence the window is called the sliding window. When the source has sent the number of segments allowed by the window, it cannot send any further segments till an acknowledgement is received from the destination. On networks with high error rates or issues, decreasing the window size can result in more reliable transmission, as the receiver will need to acknowledge fewer segments. With a large window size, the sender will need to resend all the frames if a single one is not received by the receiver.