Q1. - (Topic 1)
Which port state is introduced by Rapid-PVST?
A. learning
B. listening
C. discarding
D. forwarding
Answer: C
Explanation:
Spanning Tree from PVST+ to Rapid-PVST Migration Configuration Example Reference 1: http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example 09186a00807b0670.shtml
Reference 2: http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cf a.shtml
PVST+ is based on IEEE802.1D Spanning Tree Protocol (STP). But PVST+ has only 3 port states (discarding, learning and forwarding) while STP has 5 port states (blocking, listening, learning, forwarding and disabled). So discarding is a new port state in PVST+.
Background Information
802.1D Spanning Tree Protocol (STP) has a drawback of slow convergence. Cisco
Catalyst switches support three types of STPs, which are PVST+, rapid-PVST+ and MST.
PVST+ is based on IEEE802.1D standard and includes Cisco proprietary extensions such
as BackboneFast, UplinkFast, and PortFast. Rapid-PVST+ is based on IEEE 802.1w
standard and has a faster convergence than 802.1D. RSTP (IEEE 802.1w) natively
includes most of the Cisco proprietary enhancements to the 802.1D Spanning Tree, such
as BackboneFast and UplinkFast. Rapid-PVST+ has these unique features:
Uses Bridge Protocol Data Unit (BPDU) version 2 which is backward compatible with the
802.1D STP, which uses BPDU version 0.
All the switches generate BPDUs and send out on all the ports every 2 seconds, whereas
in 802.1D STP only the root bridge sends the configuration BPDUs.
Port Roles—Root port, designated port, alternate port and backup port.
Port States—Discarding, Learning, and Forwarding.
Port Types—Edge Port (PortFast), Point-to-Point and Shared port.
Rapid-PVST uses RSTP to provide faster convergence. When any RSTP port receives
legacy 802.1D BPDU, it falls back to legacy STP and the inherent fast convergence
benefits of 802.1w are lost when it interacts with legacy bridges.
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 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).
Q4. - (Topic 1)
Which two states are the port states when RSTP has converged? (Choose two.)
A. discarding
B. listening
C. learning
D. forwarding
E. disabled
Answer: A,D
Explanation:
Understanding Rapid Spanning Tree Protocol (802.1w)
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cf a.shtml
Port States There are only three port states left in RSTP that correspond to the three possible operational states. The 802.1D disabled, blocking, and listening states are merged into a unique 802.1w discarding state. RSTP only has 3 port states which are discarding, learning and forwarding. When RSTP has converged there are only 2 port states left: discarding and forwarding.
Q5. - (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.
Q6. - (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.
Q7. DRAG DROP - (Topic 3)
Answer:
Explanation:
1) a router is this type of device: DTE2) the most common type of virtual circuit: PVC3) provides status messages between DTE and DCE devices: LMI4) identifies the virtual connection between the DTE and the switch: DLCI
CCNA Certification Test Prep Case Study http://www.thebryantadvantage.com/CCNACertificationExamTutorialDirectlyConnectedSeri alInterfaces.htm Configuring the LMI Type on a Frame Relay Interface http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=3 Frame Relay DLCIs And Mappings http://www.mcmcse.com/cisco/guides/frame_relay_dlci.shtml
Q8. - (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
Q9. - (Topic 2)
Refer to the exhibit.
What information about the interfaces on the Main_Campus router is true?
A. The LAN interfaces are configured on different subnets.
B. Interface FastEthernet 0/0 is configured as a trunk.
C. The Layer 2 protocol of interface Serial 0/1 is NOT operational.
D. The router is a modular router with five FastEthernet interfaces.
E. Interface FastEthernet 0/0 is administratively deactivated.
Answer: B
Explanation:
Interface fa0/0 breaks into sub-interfaces and Main_Campus router is connected with switch via fa0/0 .Subinterfaces configured with different subnet masks so the same switch has multiple vlans and allows communication between these VLAN's. For routing and inter-vlan we need to configure a trunk port. So B will be the correct answer.
Q10. - (Topic 2)
Which statement describes the process ID that is used to run OSPF on a router?
A. It is globally significant and is used to represent the AS number.
B. It is locally significant and is used to identify an instance of the OSPF database.
C. It is globally significant and is used to identify OSPF stub areas.
D. It is locally significant and must be the same throughout an area.
Answer: B
Explanation: The Process ID for OSPF on a router is only locally significant and you can use the same number on each router, or each router can have a different number-it just doesn't matter. The numbers you can use are from 1 to 65,535. Don't get this confused with area numbers, which can be from 0 to 4.2 billion.