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Q1. - (Topic 1)
Which three statements about RSTP are true? (Choose three.)
A. RSTP significantly reduces topology reconverging time after a link failure.
B. RSTP expands the STP port roles by adding the alternate and backup roles.
C. RSTP port states are blocking, discarding, learning, or forwarding.
D. RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.
E. RSTP also uses the STP proposal-agreement sequence.
F. RSTP uses the same timer-based process as STP on point-to-point links.
Answer: A,B,D
Explanation:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cf
a.shtml
Convergence
Cisco enhanced the original 802.1D specification with features such as Uplink Fast,
Backbone Fast, and Port Fast to speed up the convergence time of a bridged network. The
drawback is that these mechanisms are proprietary and need additional configuration.
Alternate and Backup Port Roles
These two port roles correspond to the blocking state of 802.1D. A blocked port is defined
as not being the designated or root port. A blocked port receives a more useful BPDU than
the one it sends out on its segment.
Remember that a port absolutely needs to receive BPDUs in order to stay blocked. RSTP
introduces these two roles for this purpose.
Rapid Transition to Forwarding State
Rapid transition is the most important feature introduced by 802.1w. The legacy STA
passively waited for the network to converge before it turned a port into the forwarding
state. The achievement of faster convergence was a matter of tuning the conservative
default parameters (forward delay and max_age timers) and often put the stability of the
network at stake. The new rapid STP is able to actively confirm that a port can safely
transition to the forwarding state without having to rely on any timer configuration. There is
now a real feedback mechanism that takes place between RSTP-compliant bridges. In order to achieve fast convergence on a port, the protocol relies upon two new variables: edge ports and link type.
Q2. - (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
Q3. DRAG DROP - (Topic 2)
Answer:
Explanation:
+ holddown timer: prevents a router from improperly reinstating a route from a regular routing update
+ split horizon: prevents information about a route from being sent in the direction from which the route was learned
+ defining a maximum: prevents invalid updates from looping the internetwork indefinitely
+ route poisoning: causes a routing protocol to advertise an infinite metric for a failed route
+ triggered update: decreases convergence time by immediately sending route information in response to a topology change
Q4. - (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)
Q5. - (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.
Q6. - (Topic 3)
Which protocol is an open standard protocol framework that is commonly used in VPNs, to provide secure end-to-end communications?
A. RSA
B. L2TP
C. IPsec
D. PPTP
Answer: C
Explanation:
Internet Protocol Security (IPsec) is a technology protocol suite for securing Internet Protocol (IP) communications by authenticating and/or encrypting each IP packet of a communication session. IPsec also includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys to be used during the session.
Q7. - (Topic 1)
At which layer of the OSI model is RSTP used to prevent loops?
A. physical
B. data link
C. network
D. transport
Answer: B
Explanation: RSTP and STP operate on switches and are based on the exchange of Bridge Protocol Data Units (BPDUs) between switches. One of the most important fields in BPDUs is the Bridge Priority in which the MAC address is used to elect the Root Bridge , RSTP operates at Layer 2. http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cf a.shtml
Q8. - (Topic 2)
A router receives information about network 192.168.10.0/24 from multiple sources. What will the router consider the most reliable information about the path to that network?
A. an OSPF update for network 192.168.0.0/16
B. a static route to network 192.168.10.0/24
C. a static route to network 192.168.10.0/24 with a local serial interface configured as the next hop
D. a RIP update for network 192.168.10.0/24
E. a directly connected interface with an address of 192.168.10.254/24
F. a default route with a next hop address of 192.168.10.1
Answer: E
Explanation:
What Is Administrative Distance? http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml
Select the Best Path Administrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of the trustworthiness of the source of the routing information. Administrative distance has only local significance, and is not advertised in routing updates. Note: The smaller the administrative distance value, the more reliable the protocol. For example, if a router receives a route to a certain network from both Open Shortest Path First (OSPF) (default administrative distance - 110) and Interior Gateway Routing Protocol (IGRP) (default administrative distance - 100), the router chooses IGRP because IGRP is more reliable. This means the router adds the IGRP version of the route to the routing table.
Q9. - (Topic 1)
Which protocol provides a method of sharing VLAN configuration information between two Cisco switches?
A. STP
B. VTP
C. 802.1Q
D. RSTP
Answer: B
Explanation:
Understanding VLAN Trunk Protocol (VTP) http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52. shtml
Introduction VLAN Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst series products.
Q10. - (Topic 3)
What are two characteristics of Frame Relay point-to-point subinterfaces? (Choose two.)
A. They create split-horizon issues.
B. They require a unique subnet within a routing domain.
C. They emulate leased lines.
D. They are ideal for full-mesh topologies.
E. They require the use of NBMA options when using OSPF.
Answer: B,C
Explanation: http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=5
Configuring Frame Relay Subinterfaces On partially meshed Frame Relay networks, the problem of split horizon can be overcome by using Frame Relay subinterfaces. Frame Relay provides a mechanism to allow a physical interface to be partitioned into multiple virtual interfaces. In a similar way, using subinterfaces allows a partially meshed network to be divided into a number of smaller, fully meshed point-to-point networks. Generally, each point-to-point subnetwork is assigned a unique network address. This allows packets received on one physical interface to be sent out from the same physical interface, albeit forwarded on VCs in different subinterfaces. There are two types of subinterfaces supported by Cisco routers: point-to-point and multipoint subinterfaces.
Q11. - (Topic 2)
What is the default maximum number of equal-cost paths that can be placed into the routing table of a Cisco OSPF router?
A. 2
B. 4
C. 16
D. unlimited
Answer: B
Explanation:
4 is the default number of routes that OSPF will include in routing table if more than 4 equal cost routes exist for the same subnet. However, OSPF can include up to 16 equal cost routes in the routing table and perform load balancing amongst them. In order to configure this feature, you need to use the OSPF subcommand maximum-paths, i.e. maximum-paths 16.
Q12. - (Topic 2)
Refer to the exhibit.
Which three EIGRP routes will be present in the router R4's routing table? (Choose three.)
A. 172.16.1.0/24
B. 10.1.10.0/30
C. 10.0.0.0/8
D. 10.1.11.0/30
E. 172.16.0.0/16
F. 192.168.1.0/24
Answer: C,E,F
Explanation:
EIGRP performs an auto-summarization each time it crosses a border between two different major networks, so when R2 advertises the routes to R4 it will advertise only the summarized routes of 10.0.0.0/8 and 172.16.0.0/16, along with the 192.168.1.0/24 route coming from R3.
Q13. - (Topic 2)
What is the default administrative distance of OSPF?
A. 90
B. 100
C. 110
D. 120
Answer: C
Explanation:
Default Distance Value Table This table lists the administrative distance default values of the protocols that Cisco supports:
Q14. - (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)
Q15. - (Topic 2)
Refer to the exhibit.
When running EIGRP, what is required for RouterA to exchange routing updates with RouterC?
A. AS numbers must be changed to match on all the routers
B. Loopback interfaces must be configured so a DR is elected
C. The no auto-summary command is needed on Router A and Router C
D. Router B needs to have two network statements, one for each connected network
Answer: A Explanation:
Here we required same autonomous system between router A,B,C.Routing updated always exchange between in same EIGRP EIGRP autonomous system.you can configure more than one EIGRP autonomous system on the same router. This is typically done at a redistribution point where two EIGRP autonomous systems are interconnected. Individual router interfaces should only be included within a single EIGRP autonomous system. Cisco does not recommend running multiple EIGRP autonomous systems on the same set of interfaces on the router. If multiple EIGRP autonomous systems are used with multiple points of mutual redistribution, it can cause discrepancies in the EIGRP topology table if correct filtering is not performed at the redistribution points. If possible, Cisco recommends you configure only one EIGRP autonomous system in any single autonomous system. http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml
Q16. - (Topic 2)
Refer to the exhibit.
If the router Cisco returns the given output and has not had its router ID set manually, what value will OSPF use as its router ID?
A. 192.168.1.1
B. 172.16.1.1
C. 1.1.1.1
D. 2.2.2.2
Answer: D
Explanation:
If a router-id is not configured manually in the OSPF routing process the router will automatically configure a router-id determined from the highest IP address of a logical interface (loopback interface) or the highest IP address of an active interface. If more than one loopback interfaces are configured, the router will compare the IP addresses of each of the interfaces and choose the highest IP address from the loopbacks.