CISCO CCNA 200-301 Q170

You are the network administrator for your company and have configured Cisco Discovery Protocol (CDP) in your network. You recently noticed that when devices send large numbers of CDP neighbor announcements, some devices are crashing. You decide to disable CDP on the router.

Which command should you use to achieve the objective?

A. no cdp run
B. set cdp disable
C. no cdp enable
D. no cdp advertise-v2

Correct Answer: A

Explanation:
You should use the no cdp run command to disable CDP on the router. Due to a known vulnerability regarding the handling of CDP by Cisco routers and switches when devices send large numbers of CDP neighbor announcements, some devices can crash or cause abnormal system behavior. To overcome this problem, you can disable CDP for the entire router by using the no cdp run command.

You cannot use the set cdp disable command to disable CDP on the router. This command disables CDP on an entire Catalyst switch. You cannot use the no cdp enable command to disable CDP on the router. This command disables CDP on a specific interface.

You cannot use the no cdp advertise-v2 command to disable CDP on the router. This command disables CDPv2 advertisements.

CISCO CCNA 200-301 Q169

You instructed your assistant to add a new router to the network. The routers in your network run OSPF. The existing router, OldRouter, is configured as follows:

router ospf 1
network 192.168.5.0 0.0.0.255 area 0
network 192.168.10.0 0.0.0.255 area 0

The OldRouter interface that connects to NewRouter is 192.168.5.3/24. Your assistant shows you the configuration that will be implemented:

newrouter(config)# router ospf 1
newrouter(config-router)# network 192.168.5.0 255.255.255.0 area 0

What is wrong with this configuration?

A. The area ID is incorrectly configured.
B. The wildcard mask is incorrectly configured.
C. The network statement is incorrectly configured.
D. The process ID number is incorrectly configured.

Correct Answer: B

Explanation:
When entering network statements for OSPF, a wildcard mask is used instead of a regular mask. Since the network connecting the two routers is a class C network, as shown by the address 192.168.5.0/24, the wildcard mask should be 0.0.0.255 rather than 255.255.255.0. With wildcard masks, the 0s octets must match, and the 255s octets do not have to match.

The area ID is correct. OldRouter is in area 0, so NewRouter should be as well. There must be an area 0 in an OSPF network. There can be multiple areas as well, but they must all connect to area 0. If non-0 areas cannot be directly connected to area 0, they must be configured with a virtual link across an area that does connect to the backbone (area 0).

The network statement is correct. The network between the routers is 192.168.5.0.

The process ID number is correct. The number is stated as OSPF 1 on OldRouter and OSPF 1 on NewRouter. They match in this case but that is not required. Process IDs are only locally significant.

CISCO CCNA 200-301 Q168

Which Wide Area Network (WAN) switching technology is used by Asynchronous Transfer Mode (ATM)?

A. packet switching
B. virtual switching
C. circuit switching
D. cell switching

Correct Answer: D

Explanation:
Cell switching is a WAN switching technology that is used by ATM. ATM is an International Telecommunication Union-Telecommunications (ITU-T) standard for transmission of data, voice, or video traffic using a fixed size frame of 53 bytes, known as cells. Out of these 53 bytes, the initial five bytes are header information and the rest 48 bytes is the payload.

Packet switching is incorrect because packet switching is popularly used for data transfer, as data is not delay sensitive and it does not require real time transfer from a sender to a receiver. With packet switching, the data is broken into labeled packets and transmitted using packet-switching networks.

Virtual switching is incorrect because no such WAN switching technology exists.

Circuit switching is incorrect because circuit switching dynamically establishes a virtual connection between a source and destination. The virtual connection cannot be used by other callers unless the circuit is released. Circuit switching is the most common technique used by the Public Switched Telephone Network (PSTN) to make phone calls. A dedicated circuit is temporarily established for the duration of call between caller and receiver. Once the caller or receiver hangs up the phone, the circuit is released and is available for other users.

CISCO CCNA 200-301 Q167

You are configuring the link between a Cisco 2950 series switch and a Cisco 2611 router. You have physically connected the router’s Ethernet port to the switch using a straight-through cable. The switch has not been configured, except for a hostname. The router’s hostname has also been configured, and the Ethernet port has been enabled. However, you forgot to assign an IP address to the Ethernet port.

You issue the show cdp neighbors command and get the following output:

If you did not configure IP addresses, how is this information being passed between the two devices?

A. The devices established a connection using default IP addresses.
B. The ip unnumbered command has been issued, which means the interface does not require an IP address to be configured.
C. CDP is a Layer 2 protocol and does not require IP addresses to be configured.
D. CDP uses its own IP addressing system.

Correct Answer: C

Explanation:
CDP is a Layer 2 protocol and does not require IP addresses to be configured. The structure of the OSI model requires that the upper-layer protocols rely on the lower-layer protocols for operation. Protocols at Layer 3 cannot be operational unless Layers 1 and 2 are operational. Conversely, lower-layer protocols do not rely on upper-layer protocols for their operation. Because CDP operates at Layer 2 of the OSI model, it does not require an IP address to be active, since IP addresses are a function of Layer 3.

The ip unnumbered command has not been issued in this scenario. This command can only be used on serial interfaces, not Ethernet interfaces. It allows a serial interface to use an address that is already applied to an Ethernet interface.

Information is not being passed between the devices through default IP addresses. There is no such thing as default IP addresses on Ethernet interfaces for Cisco routers.

Information is not being passed between the devices through CDP’s IP addressing system. CDP does not have its own IP addressing system because it does not use IP addresses for its operation.

CISCO CCNA 200-301 Q166

Which of the following is a Point-to-Point Protocol (PPP) authentication protocol that supports sending of hashed values instead of sending passwords in clear text?

A. LCP
B. NCP
C. PAP
D. CHAP

Correct Answer: D

Explanation:
There are two authentication methods available when implementing a PPP connection: Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP).

Challenge Handshake Authentication Protocol (CHAP) uses a one-way hash function based on the Message Digest 5 (MD5) hashing algorithm to hash the password. This hashed value is then sent across the wire. In this situation, the actual password is never sent. No one tapping the wire will be able to reverse the
hash to come up with the original password. This is why MD5 is referred to as a one-way function. It cannot be reverse engineered. CHAP uses a three-way handshake process to perform the authentication. Moreover, CHAP periodically repeats the authentication process after link establishment.

When configuring PPP with CHAP authentication, both routers must be configured with a username that will be presented by the other router with a password. Therefore, the username to configure on Router A will be the username of Router B. The password should be the same on both machines. If these settings are not correct, then authentication will fail. The authentication process can be displayed as it happens with the debug PPP authentication command.

Link Control protocol (LCP) is defined in Request for Comments (RFCs) 1548 and 1570 and has primary responsibility to establish, configure, authenticate, and test a PPP connection. LCP negotiates the following when setting up a PPP connection:

– Authentication method used (PAP or CHAP), if any
– Compression algorithm used (Stacker or Predictor), if any
– Callback phone number to use, if defined
– Multilink; other physical connections to use, if configured

Network Control Protocol (NCP) defines the process for how the two PPP peers negotiate which network layer protocols, such as IP and IPX, will be used across the PPP connection. LCP is responsible for negotiating and maintaining a PPP connection whereas NCP is responsible for negotiating upper-layer protocols that will be carried across the PPP connection.

Password authentication Protocol (PAP) is simpler than CHAP, but less secure. During the authentication phase, PAP goes through a two-way handshake process. In this process, the source sends its user name (or hostname) and password in clear text, to the destination. The destination compares this information with a list of locally stored user names and passwords. If it finds a match, the destination returns an accept message. If it does not find a match, it returns a reject message.

CISCO CCNA 200-301 Q165

With which type of service is bandwidth and latency the biggest consideration?

A. streaming video
B. telnet sessions
C. FTP transfers
D. authentication traffic

Correct Answer: A

Explanation:
Streaming video places the largest demand on both bandwidth and latency. Video traffic is real-time and benefits from dedicated bandwidth with QoS implementation to ensure quality. Moreover, this service can tolerate very little latency.

Telnet and FTP sessions are both low bandwidth users and can tolerate a high degree of latency since the data can be reassembled when all pieces arrive, which is not possible when data is coming in real-time, and waiting for retransmissions and reassembly is not feasible.

Authentication traffic is not sensitive to latency and does not require much bandwidth either.

CISCO CCNA 200-301 Q164

You are the network administrator for your company. You recently configured Cisco Discovery Protocol (CDP) in the network. You want to view output regarding all of the neighboring devices discovered by CDP. This information should include network address, enabled protocols, and hold time.

Which Cisco Internetwork Operating System (IOS) command would allow you to accomplish this task?

A. show cdp
B. show cdp entry
C. show cdp neighbor entries
D. show cdp neighbors detail

Correct Answer: D

Explanation:
In this scenario, you should use the show cdp neighbors detail command to view the details of the neighboring devices that were discovered by CDP. CDP is a Layer 2 (data link layer) protocol used to find information about neighboring network devices. The show cdp neighbors detail command is used to view details such as network address, enabled protocols, and hold time. The complete syntax of this command is:

show cdp neighbors [type number] [detail]

The command parameters are defined in this way:

type: An optional parameter which specifies the type of interface used to connect to the neighbors for which you require information.

number: An optional parameter used to specify the interface number connected to the neighbors for which you want information.

detail: An optional parameter used to get detailed information about neighboring devices, such as network address, enabled protocols, software version and hold time.

The show cdp command is incorrect because this command is used to view global CDP information such as the timer and hold time. The show cdp entry command is incorrect because this command is used to view information about a specific neighboring device.

The show cdp neighbor entries command is incorrect because this is not a valid Cisco IOS command.

CISCO CCNA 200-301 Q163

If a routing table contains multiple routes for the same destination, which were inserted by the following methods, which route will the router use to reach the destination network?

A. The route inserted by RIP
B. The route inserted by OSPF
C. The route inserted by BGP
D. The route configured as a static route

Correct Answer: D

Explanation:
A static route will be preferred because it has the lowest administrative distance. Routing protocols are dynamic routing methods. With the default configuration, static routes are preferred over dynamic routes.

The default administrative distance for the offered options is:
– RIP 120
– OSPF 110
– eBGP 20
– Static 1

When Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), and static routing is enabled on a router, the router will prefer the static route.

CISCO CCNA 200-301 Q162

Which of the following is NOT a mode of Dynamic Trunking Protocol (DTP)?

A. dynamic auto
B. dynamic trunk
C. dynamic desirable
D. nonegotiate

Correct Answer: B

Explanation:
Dynamic trunk is not a DTP mode. DTP is a Cisco proprietary trunk negotiation protocol and is used to determine if two interfaces on connected devices can become a trunk. There are five modes of DTP:

Trunk: Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link. The interface becomes a trunk interface even if the neighboring interface does not agree to the change.

Access: Puts the interface into permanent nontrunking mode and negotiates to convert the link into a nontrunk link. The interface becomes a nontrunk interface even if the neighboring interface does not agree to the change.

Dynamic desirable: Makes the interface actively attempt to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode.

Dynamic auto: Makes the interface willing to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk or desirable mode. This is the default mode for all Ethernet interfaces in Cisco IOS.

Nonegotiate: Puts the interface into permanent trunking mode but prevents the interface from generating DTP frames. You must configure the neighboring interface manually as a trunk interface to establish a trunk link. Use this mode when connecting to a device that does not support DTP.

If one side’s mode of link is in trunk mode, dynamic desirable mode, or dynamic auto mode, and the other side is trunk or dynamic desirable, a trunk will form. Nonegotiate mode enables trunking but disables DTP.

CISCO CCNA 200-301 Q161

Which command is NOT mandatory for inclusion in a plan to implement IP Service Level Agreements (SLAs) to monitor IP connections and traffic?

A. ip sla
B. ip sla schedule
C. ip sla reset
D. icmp-echo

Correct Answer: C

Explanation:
The ip sla reset command is not mandatory for an implementation plan to configure IP SLAs for monitoring IP connections and traffic. This command causes the IP SLA engine to either restart or shutdown. As a result, all IP SLAs operations are stopped, IP SLA configuration information is erased, and IP SLAs are restarted.

The IP SLAs configuration information will need to be reloaded to the engine.
The following commands are essential to the implementation plan:

ip sla
ip sla schedule icmp-echo

The ip sla command allows you to configure IP SLAs operations. When you execute this command in the global configuration mode, it enables the IP SLA configuration mode. In the IP SLA configuration mode, you can configure different IP SLA operations. You can configure up to 2000 operations for a given IP SLA ID number.

The icmp-echo command allows you to monitor IP connections and traffic on routers by creating an IP SLA ICMP Echo operation. This operation monitors end-to- end response times between routers.

The ip sla schedule command allows you to schedule the IP SLA operation that has been configured. With this command, you can specify when the operation starts, how long the operation runs, and the how long the operation gathers information.

For example, if you execute the ip sla schedule 40 start-time now life forever command, the IP SLA operation with the identification number 40 immediately starts running. This is because the now keyword is specified for the start-time parameter. Using the forever keyword with the life parameter indicates that the operation keeps collecting information indefinitely. Note that you cannot re-configure the IP SLA operation after you have executed the ip sla schedule command.