Q1. - (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)
Q2. - (Topic 3)
Refer to the exhibit.
A network associate has configured OSPF with the command: City(config-router)# network 192.168.12.64 0.0.0.63 area 0 After completing the configuration, the associate discovers that not all the interfaces are participating in OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this configuration statement? (Choose three.)
A. FastEthernet0 /0
B. FastEthernet0 /1
C. Serial0/0
D. Serial0/1.102
E. Serial0/1.103
F. Serial0/1.104
Answer: B,C,D
Explanation:
The “network 192.168.12.64 0.0.0.63 equals to network 192.168.12.64/26. This network has:Increment: 64 (/26= 1111 1111.1111 1111.1111 1111.1100 0000)Network address:
192.168.12.64 Broadcast address: 192.168.12.127Therefore all interface in the range of this network will join OSPF - B C D are correct.
Q3. - (Topic 2)
When a router undergoes the exchange protocol within OSPF, in what order does it pass through each state?
A. exstart state > loading state > exchange state > full state
B. exstart state > exchange state > loading state > full state
C. exstart state > full state > loading state > exchange state
D. loading state > exchange state > full state > exstart state
Answer: B
Explanation:
OSPF states for adjacency formation are (in order) Down, Init, Attempt, 2-way, Exstart,
Exchange, Loading and Full.
Reference:
Why Are OSPF Neighbors Stuck in Exstart/Exchange State?
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f0d.shtml
Q4. - (Topic 2)
What are three characteristics of the OSPF routing protocol? (Choose three.)
A. It converges quickly.
B. OSPF is a classful routing protocol.
C. It uses cost to determine the best route.
D. It uses the DUAL algorithm to determine the best route.
E. OSPF routers send the complete routing table to all directly attached routers.
F. OSPF routers discover neighbors before exchanging routing information.
Answer: A,C,F
Explanation:
Open Shortest Path First Reference:
http://docwiki.cisco.com/wiki/Open_Shortest_Path_First
Explanation:
Additional OSPF features include equal-cost, multipath routing, and routing based on upper-layer type-of-service (TOS) requests. TOS-based routing supports those upper-layer protocols that can specify particular types of service. An application, for example, might specify that certain data is urgent. If OSPF has high-priority links at its disposal, these can be used to transport the urgent datagram.
OSPF supports one or more metrics. If only one metric is used, it is considered to be arbitrary, and TOS is not supported. If more than one metric is used, TOS is optionally supported through the use of a separate metric (and, therefore, a separate routing table) for each of the eight combinations created by the three IP TOS bits (the delay, throughput, and reliability bits). For example, if the IP TOS bits specify low delay, low throughput, and high reliability, OSPF calculates routes to all destinations based on this TOS designation. IP subnet masks are included with each advertised destination, enabling variable-length subnet masks. With variable-length subnet masks, an IP network can be broken into many subnets of various sizes. This provides network administrators with extra network-configuration flexibility.
Q5. - (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)
Q6. - (Topic 3)
The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
A. This command should be executed from the global configuration mode.
B. The IP address 10.121.16.8 is the local router port used to forward data.
C. 102 is the remote DLCI that will receive the information.
D. This command is required for all Frame Relay configurations.
E. The broadcast option allows packets, such as RIP updates, to be forwarded across the PVC.
Answer: E
Explanation:
The command frame-relay map ip 10.121.16.8 102 broadcast means to map the remote IP
10.121.16.8 to the local DLCI 102. When the “broadcast” keyword is included, it turns Frame Relay network as a broadcast network, which can forward broadcasts.
Q7. - (Topic 2)
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?
A. Any packet destined for a network that is not directly connected to router R1 will be dropped.
B. Any packet destined for a network that is not directly connected to router R2 will be dropped immediately.
C. 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.
D. The networks directly connected to router R2 will not be able to communicate with the 172.16.100.0, 172.16.100.128, and 172.16.100.64 subnetworks.
E. 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.
Answer: E
Explanation:
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 (172.16.100.0 0.0.0.3, 172.16.100.64 0.0.0.63, 172.16.100.128 0.0.0.31) so the packets destined for these networks will not be affected by the default route. The default route configured on R1 "ip route 0.0.0.0 0.0.0.0 serial0/0 will send any packet whose destination network is not referenced in the routing table of router R1 to R2, it doesn't drop anything so answers A, B and C are not correct. D is not correct too because these routes are declared in R1 and the question says that "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.
Q8. - (Topic 1)
Which two of these statements regarding RSTP are correct? (Choose two.)
A. RSTP cannot operate with PVST+.
B. RSTP defines new port roles.
C. RSTP defines no new port states.
D. RSTP is a proprietary implementation of IEEE 802.1D STP.
E. RSTP is compatible with the original IEEE 802.1D STP.
Answer: B,E
Explanation:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cf a.shtml
Port Roles The role is now a variable assigned to a given port. The root port and designated port roles remain, while the blocking port role is split into the backup and alternate port roles. The Spanning Tree Algorithm (STA) determines the role of a port based on Bridge Protocol Data Units (BPDUs). In order to simplify matters, the thing to remember about a BPDU is there is always a method to compare any two of them and decide whether one is more useful than the other. This is based on the value stored in the BPDU and occasionally on the port on which they are received. This considered, the information in this section explains practical approaches to port roles.
Compatibility with 802.1D RSTP is able to interoperate with legacy STP protocols. However, it is important to note that the inherent fast convergence benefits of 802.1w are lost when it interacts with legacy bridges.
Q9. - (Topic 2)
Refer to the exhibit.
From R1, a network administrator is able to ping the serial interface of R2 but, unable to ping any of the subnets attached to RouterB. Based on the partial outputs in the exhibit, what could be the problem?
A. EIGRP does not support VLSM.
B. The EIGRP network statements are incorrectly configured.
C. The IP addressing on the serial interface of RouterA is incorrect.
D. The routing protocol has summarized on the classful boundary.
E. EIGRP has been configured with an invalid autonomous system number.
Answer: D
Explanation:
CCNA - EIGRP Common Question Reference:
http://www.orbitco-ccna-pastquestions.com/CCNA---EIGRP-Common-Question.php
Explanation:
If you look carefully at the R2 ip route, you will discover that the R2 does not learn any network from R1; this is because the routing protocol used here (EIGRP) performs auto summary when advertising routes to peers across a network. So in this case the address 172.17.0.0/16 is a summarized address. If the router was configured with no auto summary command, R2 LAN addresses would have been advertised and reached.
Q10. - (Topic 3)
Which command allows you to verify the encapsulation type (CISCO or IETF) for a Frame Relay link?
A. show frame-relay lmi
B. show frame-relay map
C. show frame-relay pvc
D. show interfaces serial
Answer: B
Explanation: map will show frame relay encapsulation (cisco or ietf) http://www.cisco.com/en/US/docs/ios/12_2/wan/command/reference/wrffr4.html#wp102934
"show frame-relay map" will show frame relay encapsulation type (CISCO or IETF)