CISCO CCNA 200-301 Q146

Which of the following are Wide Area Network (WAN) protocols? (Choose three.)

F. Frame Relay

Correct Answer: A, E, F

Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC), and Frame Relay are WAN protocols.

PPP is a WAN protocol is defined in Request for Comments (RFCs) 1332, 1661, and 2153. PPP works with asynchronous and synchronous serial interfaces as well as High-Speed Serial Interfaces (HSSI) and Integrated Services Digital Network (ISDN) interfaces (BRI and PRI).

Some of the characteristics of PPP are:
– Can be used over analog circuits
– Can encapsulate several routed protocols, such as TCP/IP Provides error correction
– Should be used rather than HDLC when non-Cisco routers are involved, as it is implemented consistently among vendors PPP authentication can be used between the routers to prevent unauthorized callers from establishing an ISDN circuit

To change the encapsulation from the default of HDLC to PPP when connecting to a non-Cisco router, such as a Juniper, you would use the following command:

router(config)#interface serial S0 router(config-if)#encapsulation ppp

HDLC is a WAN protocol used with synchronous and asynchronous connections. It defines the frame type and interaction between two devices at the Data Link layer.

Frame Relay is a group of WAN protocols, including those from International Telecommunication Union (ITU-T) and American National Standards Institute (ANSI). Frame Relay defines interaction between the Frame Relay customer premises equipment (CPE) and the Frame Relay carrier switch. The connection across the carrier’s network is not defined by the Frame Relay standards. Most carriers, however, use Asynchronous Transfer Mode (ATM) as a transport to move Frame Relay frames between different sites.

Authentication, Authorization, and Accounting (AAA) is incorrect because this is a scheme to monitor access control and activities on networked devices. Wired Equivalent Privacy (WEP) is a security scheme for wireless networks and therefore it is incorrect.

Spanning Tree Protocol (STP) is for loop avoidance in redundant topologies. This option is incorrect because this protocol is used on Local Area Network (LAN).

CISCO CCNA 200-301 Q85

In the given exhibit, which combination shows the components of a bridge ID used for Spanning Tree Protocol (STP)?

A. 1
B. 2
C. 3
D. 4

Correct Answer: C

The bridge ID, also known as the switch ID, is used to elect the root bridge in a redundant network topology. The bridge ID has two components:

– Switch’s priority number: Configured as 32768 on Cisco switches by default
– Switch’s Media Access Control (MAC) address: The burnt-in hardware address of the network interface card (NIC)

The switch with the lowest bridge ID is elected as the root bridge. If the same priority number is configured on two or more switches in the network, the switch with the lowest MAC address will become the root.

Bridge Protocol Data Units (BPDUs) communicate the details of the switch with the lowest bridge ID in the network. The election process for the root bridge takes place every time there is a topology change in the network. A topology change may occur due to the failure of a root bridge or the addition of a new switch in the network. The root bridge originates BPDUs every two seconds, which are propagated by other switches throughout the network. BPDUs are used as keepalives between switches. If a switch stops receiving BPDUs from a neighboring switch for ten intervals (20 seconds), it will assume a designated role for the network segment.

The combinations of the remaining options are incorrect because Virtual LAN (VLAN) numbers and serial numbers are not components of a bridge ID. Objective:

CISCO CCNA Exam – Q277

Refer to the exhibit.
CISCO CCNA Exam – Q277

A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch1 is disconnected. What would be an effect of this cable being disconnected?

A. Host B would not be able to access the server in VLAN9 until the cable is reconnected.
B. Communication between VLAN3 and the other VLANs would be disabled.
C. The transfer of files from Host B to the server in VLAN9 would be significantly slower.
D. For less than a minute, Host B would not be able to access the server in VLAN9. Then normal network function would resume.

Correct Answer: D

Spanning-Tree Protocol (STP) is a Layer 2 protocol that utilizes a special-purpose algorithm to discover physical loops in a network and effect a logical loop-free topology. STP creates a loop-free tree structure consisting of leaves and branches that span the entire Layer 2 network. The actual mechanics of how bridges communicate and how the STP algorithm works will be discussed at length in the following topics. Note that the terms bridge and switch are used interchangeably when discussing STP. In addition, unless otherwise indicated, connections between switches are assumed to be trunks.


Based on the network shown in the graphic

Which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?

A. routing loops, hold down timers
B. switching loops, split horizon
C. routing loops, split horizon
D. switching loops, VTP
E. routing loops, STP
F. switching loops, STP

Correct Answer: F

The Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.