Q1. - (Topic 1)
Refer to the exhibit.
What commands must be configured on the 2950 switch and the router to allow communication between host 1 and host 2? (Choose two.)
A. Router(config)# interface fastethernet 0/0 Router(config-if)# ip address 192.168.1.1 255.255.255.0 Router(config-if)# no shut down
B. Router(config)# interface fastethernet 0/0 Router(config-if)# no shut down Router(config)# interface fastethernet 0/0.1 Router(config-subif)# encapsulation dot1q 10 Router(config-subif)# ip address 192.168.10.1 255.255.255.0
Router(config)# interface fastethernet 0/0.2 Router(config-subif)# encapsulation dot1q 20 Router(config-subif)# ip address 192.168.20.1 255.255.255.0
C. Router(config)# router eigrp 100 Router(config-router)# network 192.168.10.0 Router(config-router)# network 192.168.20.0
D. Switch1(config)# vlan database Switch1(config-vlan)# vtp domain XYZ Switch1(config-vlan)# vtp server
E. Switch1(config)# interface fastethernet 0/1 Switch1(config-if)# switchport mode trunk
F. Switch1(config)# interface vlan 1 Switch1(config-if)# ip default-gateway 192.168.1.1
Answer: B,E
Explanation:
The two answers B and E list all the commands needed to configure interVLAN routing. Please notice that Cisco switch 2950, 2960 only support dot1Q trunking so we don’t need to specify which trunking encapsulation to use in this case. For Cisco switches 3550 or above we have to use these commands instead:
Switch3550(config-if)#switchport trunk encapsulation dot1q Switch3550(config-if)#switchport mode trunk
References: http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a 00800949fd.shtml https://learningnetwork.cisco.com/servlet/JiveServlet/download/5669-2461/Router%20on%20a%20Stick.pdf.
Q2. - (Topic 3)
Users have been complaining that their Frame Relay connection to the corporate site is very slow. The network administrator suspects that the link is overloaded. Based on the partial output of the Router # show frame relay pvc command shown in the graphic, which output value indicates to the local router that traffic sent to the corporate site is experiencing congestion?
A. DLCI=100
B. last time PVC status changed 00:25:40
C. in BECN packets 192
D. in FECN packets 147
E. in DF packets 0
Answer: C
Explanation:
First we should grasp the concept of BECN & FECN through an example:
Suppose Router A wants to send data to Router B through a Frame Relay network. If the network is congested, Switch 1 (a DCE device) will set the FECN bit value of that frame to 1, indicating that frame experienced congestion in the path from source to destination. This frame is forwarded to Switch 2 and to Router B (with the FECN bit = 1). Switch 1 knows that the network is congesting so it also sends frames back to Router A with BECN bit set to 1 to inform that path through the network is congested.
In general, BECN is used on frames traveling away from the congested area to warn source devices that congestion has occurred on that path while FECN is used to alert receiving devices if the frame experiences congestion.
BECN also informs the transmitting devices to slow down the traffic a bit until the network returns to normal state. The question asks “which output value indicates to the local router that traffic sent to the corporate site is experiencing congestion” which means it asks about the returned parameter which indicates congestion ->BECN.
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 1)
What are two characteristics of a switch that is configured as a VTP client? (Choose two.)
A. If a switch that is configured to operate in client mode cannot access a VTP server, then the switch reverts to transparent mode.
B. On switches that are configured to operate in client mode, VLANs can be created, deleted, or renamed locally.
C. The local VLAN configuration is updated only when an update that has a higher configuration revision number is received.
D. VTP advertisements are not forwarded to neighboring switches that are configured in VTP transparent mode.
E. VTP client is the default VTP mode.
F. When switches in VTP client mode are rebooted, they send a VTP advertisement request to the VTP servers.
Answer: C,F
Explanation:
VLAN Trunking Protocol (VTP) http://archive.networknewz.com/2004/0317.html
VTP Modes Server Mode Once VTP is configured on a Cisco switch, the default mode used is Server Mode. In any given VTP management domain, at least one switch must be in Server Mode. When in Server Mode, a switch can be used to add, delete, and modify VLANs, and this information will be passed to all other switches in the VTP management domain. Client Mode When a switch is configured to use VTP Client Mode, it is simply the recipient of any VLANs added, deleted, or modified by a switch in Server Mode within the same management domain. A switch in VTP client mode cannot make any changes to VLAN information. Transparent Mode A switch in VTP Transparent Mode will pass VTP updates received by switches in Server Mode to other switches in the VTP management domain, but will not actually process the contents of these messages. When individual VLANs are added, deleted, or modified on a switch running in transparent mode, the changes are local to that particular switch only, and are not passed to other switches in the VTP management domain.
Q5. - (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
Q6. - (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.
Q7. - (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.
Q8. - (Topic 2)
What are the two default metrics used by EIGRP for route selection? (Choose two.)
A. Bandwidth
B. Delay
C. Reliability
D. Load
E. MTU
Answer: A,B
Explanation:
EIGRP adds together weighted values of different network link characteristics in order to calculate a metric for evaluating path selection.
These characteristics include:
. Delay (measured in 10s of microseconds)
. Bandwidth (measured in kilobytes per second)
. Reliability (in numbers ranging from 1 to 255; 255 being the most reliable)
. Load (in numbers ranging from 1 to 255; 255 being saturated)
Various constants (K.1.through K.5) are able to be set by a user to produce varying routing behaviors. However by default, only delay and bandwidth are used in the weighted formula to produce a single 32bit metric:
Note:.Default K values are:.K1.=.K3.= 1 and.K2.=.K4.=.K5.= 0When K5.is equal to 0 then [
K5/(.K4.+ reliability)] is defined to be 1
Use of the default constants effectively reduces the formula above to:
Reference: http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/enhanced-interior-gateway-routing-protocol-eigrp/whitepaper_C11-720525.html
Q9. - (Topic 3)
What occurs on a Frame Relay network when the CIR is exceeded?
A. All TCP traffic is marked discard eligible.
B. All UDP traffic is marked discard eligible and a BECN is sent.
C. All TCP traffic is marked discard eligible and a BECN is sent.
D. All traffic exceeding the CIR is marked discard eligible.
Answer: D
Explanation:
Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the Frame Relay switch. Frames that are sent in excess of the CIR are marked as discard eligible (DE) which means they can be dropped if the congestion occurs within the Frame Relay network. Note: In the Frame Relay frame format, there is a bit called Discard eligible (DE) bit that is used to identify frames that are first to be dropped when the CIR is exceeded.
Q10. - (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.
Q11. - (Topic 2)
Refer to the exhibit.
C-router is to be used as a "router-on-a-stick" to route between the VLANs. All the interfaces have been properly configured and IP routing is operational. The hosts in the VLANs have been configured with the appropriate default gateway. What is true about this configuration?
A. These commands need to be added to the configuration: C-router(config)# router eigrp 123 C-router(config-router)# network 172.19.0.0
B. These commands need to be added to the configuration: C-router(config)# router ospf 1 C-router(config-router)# network 172.19.0.0 0.0.3.255 area 0
C. These commands need to be added to the configuration: C-router(config)# router rip C-router(config-router)# network 172.19.0.0
D. No further routing configuration is required.
Answer: D
Explanation:
http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a 00800949fd.shtml https://learningnetwork.cisco.com/servlet/JiveServlet/download/5669-2461/Router%20on%20a%20Stick.pdf.
Q12. - (Topic 1)
What is one benefit of PVST+?
A. PVST+ supports Layer 3 load balancing without loops.
B. PVST+ reduces the CPU cycles for all the switches in the network.
C. PVST+ allows the root switch location to be optimized per VLAN.
D. PVST+ automatically selects the root bridge location, to provide optimized bandwidth usage.
Answer: C
Explanation:
Per VLAN Spanning Tree (PVST) Introduction http://www.cisco.com/en/US/tech/tk389/tk621/tk846/tsd_technology_support_sub-protocol_home.html Per VLAN Spanning Tree (PVST) maintains a spanning tree instance for each VLAN configured in the network. This means a switch can be the root bridge of a VLAN while another switch can be the root bridge of other VLANs in a common topology. For example, Switch 1 can be the root bridge for Voice data while Switch 2 can be the root bridge for Video data. If designed correctly, it can optimize the network traffic. http://www.ciscopress.com/articles/article.asp?p=102157&seqNum=4
Topic 2, Routing Technologies
Q13. - (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.
Q14. - (Topic 3)
Refer to the exhibit.
What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command shown?
A. The Serial0/0 interface is passing traffic.
B. The DLCI 100 was dynamically allocated by the router
C. The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server
D. The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud
E. The mapping between DLCI 100 and the end station IP address 172.16.3.1 was learned through Inverse ARP
Answer: E
Explanation:
The term dynamic indicates that the DLCI number and the remote router IP address
172.16.3.1 are learned via the Inverse ARP process.
Inverse ARP is a technique by which dynamic mappings are constructed in a network, allowing a device such as a router to locate the logical network address and associate it with a permanent virtual circuit (PVC).
Q15. - (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.
Q16. - (Topic 1)
Which three of these statements regarding 802.1Q trunking are correct? (Choose three.)
A. 802.1Q native VLAN frames are untagged by default.
B. 802.1Q trunking ports can also be secure ports.
C. 802.1Q trunks can use 10 Mb/s Ethernet interfaces.
D. 802.1Q trunks require full-duplex, point-to-point connectivity.
E. 802.1Q trunks should have native VLANs that are the same at both ends.
Answer: A,C,E
Explanation:
CCNA Self-Study (ICND Exam): Extending Switched Networks with Virtual LANs http://www.ciscopress.com/articles/article.asp?p=102157&seqNum=2