Q1. - (Topic 2)
What are two benefits of using a single OSPF area network design? (Choose two.)
A. It is less CPU intensive for routers in the single area.
B. It reduces the types of LSAs that are generated.
C. It removes the need for virtual links.
D. It increases LSA response times.
E. It reduces the number of required OSPF neighbor adjacencies.
Answer: B,C
Explanation:
OSPF uses a LSDB (link state database) and fills this with LSAs (link state advertisement). The link types are as follows:
LSA Type 1:. Router LSA
LSA Type 2:.. . . . . . . . Network LSA
LSA Type 3:. Summary LSA
LSA Type 4:. Summary ASBR LSA
LSA Type 5:. Autonomous system external LSA
LSA Type 6:. Multicast OSPF LSA
LSA Type 7:. Not-so-stubby area LSA
LSA Type 8:. External attribute LSA for BGP
If all routers are in the same area, then many of these LSA types (Summary ASBR LSA, external LSA, etc) will not be used and will not be generated by any router.
All areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, you can use a virtual link to connect to the backbone through a non-backbone area. You can also use virtual links to connect two parts of a partitioned backbone through a non-backbone area. The area through which you configure the virtual link, known as a transit area, must have full routing information. The transit area cannot be a stub area. Virtual links are not ideal and should really only be used for temporary network solutions or migrations. However, if all locations are in a single OSPF area this is not needed.
Q2. - (Topic 1)
Refer to the exhibit.
At the end of an RSTP election process, which access layer switch port will assume the discarding role?
A. Switch3, port fa0/1
B. Switch3, port fa0/12
C. Switch4, port fa0/11
D. Switch4, port fa0/2
E. Switch3, port Gi0/1
F. Switch3, port Gi0/2
Answer: C
Explanation:
In this question, we only care about the Access Layer switches (Switch3 & 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4. Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port? Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior than another if it has:
1. A lower Root Bridge ID2. A lower path cost to the Root3. A lower Sending Bridge ID4. A lower Sending Port ID
These four parameters are examined in order. In this specific case, all the BPDUs sent by Switch3 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID. The only parameter left to select the best one is the Sending Port ID (Port ID = port priority + port index). In this case the port priorities are equal because they use the default value, so Switch4 will compare port index values, which are unique to each port on the switch, and because Fa0/12 is inferior to Fa0/1, Switch4 will select the port connected with Fa0/1 (of Switch3) as its root port and block the other port -> Port fa0/11 of Switch4 will be blocked (discarding role)
Q3. - (Topic 2)
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
Answer: B,E
Explanation:
In the router ospf Command, the ranges from 1 to 65535 so o is an invalid number - B is correct but A is not correct. To configure OSPF, we need a wildcard in the “network” statement, not a subnet mask. We also need to assign an area to this process - E is correct.
Q4. - (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.
Q5. - (Topic 2)
What can cause two OSPF neighbors to be stuck in the EXSTART state?
A. There is a low bandwidth connection between neighbors.
B. The neighbors have different MTU settings.
C. The OSPF interfaces are in a passive state.
D. There is only layer one connectivity between neighbors.
Answer: B
Explanation:
Neighbors Stuck in Exstart/Exchange State The problem occurs most frequently when attempting to run OSPF between a Cisco router and another vendor's router. The problem occurs when the maximum transmission unit (MTU) settings for neighboring router interfaces don't match. If the router with the higher MTU sends a packet larger that the MTU set on the neighboring router, the neighboring router ignores the packet.0 When this problem occurs, the output of the show ip ospf neighbor command displays output similar that shown below: router-6# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
170.170.11.7 1 EXCHANGE/ - 00:00:36 170.170.11.7 Serial2.7 router-6# router-7# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
170.170.11.6 1 EXSTART/ - 00:00:33 170.170.11.6 Serial0.6
Reference: http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13684-12.html
Q6. - (Topic 3)
Which two statistics appear in show frame-relay map output? (Choose two.)
A. the number of BECN packets that are received by the router
B. the value of the local DLCI
C. the number of FECN packets that are received by the router
D. the status of the PVC that is configured on the router
E. the IP address of the local router
Answer: B,D
Explanation:
Frame Relay Commands (map-class frame-relay through threshold ecn)
http://www.cisco.com/en/US/docs/ios/12_2/wan/command/reference/wrffr4.html#wp102934
Examples
The following is sample output from the show frame-relay map command:
Router#show frame-relay map Serial 1 (administratively down): ip 10.108.177.177
dlci 177 (0xB1,0x2C10), static, broadcast,
CISCO
TCP/IP Header Compression (inherited), passive (inherited)
Q7. - (Topic 3)
Which two options are valid WAN connectivity methods? (Choose two.)
A. PPP
B. WAP
C. DSL
D. L2TPv3
E. Ethernet
Answer: A,C
Explanation:
On each WAN connection, data is encapsulated into frames before itcrosses the WAN link. The following are typical WAN protocols:1. High-level Data Link Control (HDLC): The Cisco default encapsulation type onpoint-to-point connections, dedicated links, and circuit-switches connections.2. PPP: Provides router-to-router and host-to-network connections over synchronous andasynchronous circuits. PPP was designed to work with several network layer protocols,including IP.3. Frame-relay: A successor to X.25. This protocol is an industry-standard, switchesdata-link layer protocol that handles multiple virtual circuits
http://en.wikipedia.org/wiki/Wide_area_network
Q8. - (Topic 3)
Refer to the exhibit.
The show interfaces serial 0/1 command was issued on the R10-1 router. Based on the output displayed which statement is correct?
A. The cable connected to the serial 0/1 interface of the R10-1 router is a DTE cable.
B. The R10-1 router can ping the router interface connected to the serial 0/1 interface.
C. The clock rate used for interface serial 0/1 of the R10-1 router is 1,544,000 bits per second.
D. The CSU used with the serial 0/1 interface of the R10-1 router has lost connection to the service provider.
E. The interface of the remote router connected to the serial 0/1 interface of the R10-1 router is using the default serial interface encapsulation.
Answer: E
Explanation:
Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for Cisco HDLC is the default encapsulation type for the serial interfaces.
Q9. - (Topic 3)
Refer to the exhibit.
Which statement describes DLCI 17?
A. DLCI 17 describes the ISDN circuit between R2 and R3.
B. DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C. DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D. DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.
Answer: C
Explanation:
DLCI stands for Data Link Connection Identifier. DLCI values are used on Frame Relay interfaces to distinguish between different virtual circuits. DLCIs have local significance because, the identifier references the point between the local router and the local Frame Relay switch to which the DLCI is connected.
Q10. - (Topic 3)
Refer to the exhibit.
Which WAN protocol is being used?
A. ATM
B. HDLC
C. Frame Relay
D. PPP
Answer: C
Explanation:
"Show interface pos8/0/0" command showing LMI enq sent which show frame-relay encapsulation enabled on this interface. Cisco supports three different Local Management Interface (LMI) types for Frame Relay: Cisco, ANSI Annex D, and Q933-A Annex A http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=3