Q1. - (Topic 3)
Which two statements about using the CHAP authentication mechanism in a PPP link are true? (Choose two.)
A. CHAP uses a two-way handshake.
B. CHAP uses a three-way handshake.
C. CHAP authentication periodically occurs after link establishment.
D. CHAP authentication passwords are sent in plaintext.
E. CHAP authentication is performed only upon link establishment.
F. CHAP has no protection from playback attacks.
Answer: B,C
Explanation:
Understanding and Configuring PPP CHAP Authentication http://www.cisco.com/en/US/tech/tk713/tk507/technologies_tech_note09186a00800b4131. shtml
One-Way and Two-Way Authentication CHAP is defined as a one-way authentication method. However, you use CHAP in both directions to create a two-way authentication. Hence, with two-way CHAP, a separate three-way handshake is initiated by each side. In the Cisco CHAP implementation, by default, the called party must authenticate the calling party (unless authentication is completely turned off). Therefore, a one-way authentication initiated by the called party is the minimum possible authentication. However, the calling party can also verify the identity of the called party, and this results in a two-way authentication. One-way authentication is often required when you connect to non-Cisco devices.
Q2. - (Topic 2)
What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two.)
A. hello packets
B. SAP messages sent by other routers
C. LSAs from other routers
D. beacons received on point-to-point links
E. routing tables received from other link-state routers
F. TTL packets from designated routers
Answer: A,C
Explanation:
Link State Routing Protocols http://www.ciscopress.com/articles/article.asp?p=24090&seqNum=4
Link state protocols, sometimes called shortest path first or distributed database protocols, are built around a well-known algorithm from graph theory, E. W. Dijkstra'a shortest path algorithm. Examples of link state routing protocols are: Open Shortest Path First (OSPF) for IP The ISO's Intermediate System to Intermediate System (IS-IS) for CLNS and IP DEC's DNA Phase V Novell's NetWare Link Services Protocol (NLSP) Although link state protocols are rightly considered more complex than distance vector protocols, the basic functionality is not complex at all:
1. Each router establishes a relationship—an adjacency—with each of its neighbors.
2. Each router sends link state advertisements (LSAs), some
3. Each router stores a copy of all the LSAs it has seen in a database. If all works well, the databases in all routers should be identical.
4. The completed topological database, also called the link state database, describes a graph of the internetwork. Using the Dijkstra algorithm, each router calculates the shortest path to each network and enters this information into the route table.
Q3. - (Topic 2)
Refer to Exhibit:
The internetwork infrastructure of company XYZ consists of a single OSPF area as shown in the graphic. There is concern that a lack of router resources is impeding internetwork performance. As part of examining the router resources, the OSPF DRs need to be known. All the router OSPF priorities are at the default and the router IDs are shown with each router. Which routers are likely to have been elected as DR? (Choose two.)
A. Corp-1
B. Corp-2
C. Corp-3
D. Corp-4
E. Branch-1
F. Branch-2
Answer: D,F
Explanation: There are 2 segments on the topology above which are separated by Corp-3 router. Each segment will have a DR so we have 2 DRs.
To select which router will become DR they will compare their router-IDs. The router with highest (best) router-ID will become DR. 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’s physical interfaces will be chosen.
In this question, the IP addresses of loopback interfaces are not mentioned so we will consider IP addresses of all active router’s physical interfaces. Router Corp-4 (10.1.40.40)
& Branch-2 (10.2.20.20) have highest “active” IP addresses so they will become DRs.
Q4. - (Topic 3)
The output of the show frame-relay pvc command shows "PVC STATUS = INACTIVE". What does this mean?
A. The PVC is configured correctly and is operating normally, but no data packets have been detected for more than five minutes.
B. The PVC is configured correctly, is operating normally, and is no longer actively seeking the address of the remote router.
C. The PVC is configured correctly, is operating normally, and is waiting for interesting traffic to trigger a call to the remote router.
D. The PVC is configured correctly on the local switch, but there is a problem on the remote end of the PVC.
E. The PVC is not configured on the local switch.
Answer: D
Explanation: The PVC STATUS displays the status of the PVC. The DCE device creates and sends the report to the DTE devices. There are 4 statuses: ACTIVE: the PVC is operational and can transmit dataINACTIVE: the connection from the local router to the switch is working, but the connection to the remote router is not availableDELETED: the PVC is not present and no LMI information is being received from the Frame Relay switch STATIC: the Local Management Interface (LMI) mechanism on the interface is disabled (by using the “no keepalive” command). This status is rarely seen.
Q5. - (Topic 3)
What is the result of issuing the frame-relay map ip 192.168.1.2 202 broadcast command?
A. defines the destination IP address that is used in all broadcast packets on DCLI 202
B. defines the source IP address that is used in all broadcast packets on DCLI 202
C. defines the DLCI on which packets from the 192.168.1.2 IP address are received
D. defines the DLCI that is used for all packets that are sent to the 192.168.1.2 IP address
Answer: D
Explanation:
Frame-relay map ip 192.168.1.2 202 command statically defines a mapping between a network layer address and a DLCI. The broadcast option allows multicast and broadcast packets to flow across the link. The command frame-relay map ip 192.168.1.2 202 broadcast means to mapping the distal IP 192.168.1.2 202 to the local DLCI . When the “broadcast” keyword is included, it turns Frame Relay network as a broadcast network, which can forward broadcasts. http://www.cisco.com/en/US/docs/ios/wan/command/reference/wan_f2.html#wp1012264
Q6. - (Topic 2)
Refer to the exhibit.
Host A pings interface S0/0 on router 3, what is the TTL value for that ping?
A. 253
B. 252
C. 255
D. 254
Answer: A
Explanation:
From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.
The picture below shows TTL values for each interface of each router and for Host B.
Notice that Host A initializes ICMP packet with a TTL of 255:
Q7. - (Topic 3)
A network administrator needs to configure a serial link between the main office and a remote location. The router at the remote office is a non-Cisco router. How should the network administrator configure the serial interface of the main office router to make the connection?
A. Main(config)# interface serial 0/0 Main(config-if)# ip address 172.16.1.1 255.255.255.252 Main(config-if)# no shut
B. Main(config)# interface serial 0/0 Main(config-if)# ip address 172.16.1.1 255.255.255.252 Main(config-if)# encapsulation ppp Main(config-if)# no shut
C. Main(config)# interface serial 0/0 Main(config-if)# ip address 172.16.1.1 255.255.255.252 Main(config-if)# encapsulation frame-relay Main(config-if)# authentication chap Main(config-if)# no shut
D. Main(config)# interface serial 0/0 Main(config-if)#ip address 172.16.1.1 255.255.255.252 Main(config-if)#encapsulation ietf Main(config-if)# no shut
Answer: B
Explanation:
Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for sending data over synchronous serial links using HDLC. So HDLC runs only in Cisco router. PPP is not proprietary protocol it's a open source every cisco router and non-cisco router understand the PPP protocol.So we need to configure the PPP protocol if connection is between cisco and non-cisco router.
Q8. - (Topic 3)
It has become necessary to configure an existing serial interface to accept a second Frame Relay virtual circuit. Which of the following are required to solve this? (Choose three)
A. configure static frame relay map entries for each subinterface network.
B. remove the ip address from the physical interface
C. create the virtual interfaces with the interface command
D. configure each subinterface with its own IP address
E. disable split horizon to prevent routing loops between the subinterface networks
F. encapsulate the physical interface with multipoint PPP
Answer: B,C,D
Explanation:
How To Configure Frame Relay Subinterfaces http://www.orbit-computer-solutions.com/How-To-Configure-Frame-Relay-Subinterfaces.php
Step to configure Frame Relay subinterfaces on a physical interface:
1. Remove any network layer address (IP) assigned to the physical interface. If the physical interface has an address, frames are not received by the local subinterfaces.
2. Configure Frame Relay encapsulation on the physical interface using the encapsulation frame-relay command.
3. For each of the defined PVCs, create a logical subinterface. Specify the port number, followed by a period (.) and the subinterface number. To make troubleshooting easier, it is suggested that the subinterface number matches the DLCI number.
4. Configure an IP address for the interface and set the bandwidth.
5. Configure the local DLCI on the subinterface using the frame-relay interface-dlci command. Configuration Example: R1>enable R1#configure terminal R1(config)#interface serial 0/0/0 R1(config-if)#no ip address R1(config-if)#encapsulation frame-relay R1(config-if)#no shutdown R1(config-if)#exit R1(config-subif)#interface serial 0/0/0.102 point-to-point R1(config-subif)#ip address 192.168.1.245 255.255.255.252 R1(config-subif)#frame-relay interface-dlci 102 R1(config-subif)#end R1#copy running-config startup-config
Q9. - (Topic 2)
Refer to the exhibit.
What address is a feasible successor?
A. 172.16.4.0
B. 10.1.4.4
C. 10.1.2.2
D. 172.16.3.0
Answer: C Explanation:
The feasible condition states:
“To qualify as a feasible successor, a router must have an AD less than the FD of the current successor route”.
In this case, we see 10.1.2.2 shows an AD less than the current successor of 10.1.4.4
Q10. - (Topic 2)
What are two drawbacks of implementing a link-state routing protocol? (Choose two.)
A. the sequencing and acknowledgment of link-state packets B. the requirement for a hierarchical IP addressing scheme for optimal functionality
C. the high volume of link-state advertisements in a converged network
D. the high demand on router resources to run the link-state routing algorithm
E. the large size of the topology table listing all advertised routes in the converged network
Answer: B,D
Explanation:
Link State routing protocols, such as OSPF and IS-IS, converge more quickly than their distance vector routing protocols such as RIPv1, RIPv2, EIGRP and so on, through the use of flooding and triggered updates. In link state protocols, changes are flooded immediately and computed in parallel. Triggered updates improve convergence time by requiring routers to send an update message immediately upon learning of a route change. These updates are triggered by some event, such as a new link becoming available oor an existing link failing. The main drawbacks to link state routing protocols are the amount of CPU overhead involved in calculating route changes and memory resources that are required to store neighbor tables, route tables and a complete topology table. http://www.ciscopress.com/articles/article.asp?p=24090&seqNum=4