[Free] Download New Updated (October 2016) Cisco 200-105 Real Exam 81-90

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QUESTION 81

What is the purpose of Inverse ARP?

 

A.

to map a known IP address to a MAC address

B.

to map a known DLCI to a MAC address

C.

to map a known MAC address to an IP address

D.

to map a known DLCI to an IP address

E.

to map a known IP address to a SPID

F.

to map a known SPID to a MAC address

 

Correct Answer: D

Explanation:

http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=4

 

Frame-Relay (a Layer 2 protocol) uses Inverse-Arp to map a know Layer 2 Address (DLCI) to a unknow Layer 3 Address.

Dynamic Mapping

Dynamic address mapping relies on the Frame Relay Inverse Address Resolution Protocol (Inverse ARP), defined by RFC 1293, to resolve a next hop network protocol address to a local DLCI value. The Frame Relay router sends out Inverse ARP requests on its Frame Relay PVC to discover the protocol address of the remote device connected to the Frame Relay network. The responses to the Inverse ARP requests are used to populate an address-to-DLCI mapping table on the Frame Relay router or access server. The router builds and maintains this address-to-DLCI mapping table, which contains all resolved Inverse ARP requests, including both dynamic and static mapping entries.

When data needs to be transmitted to a remote destination address, the router performs a lookup on its routing table to determine whether a route to that destination address exists and the next hop address or directly connected interface to use in order to reach that destination. Subsequently, the router consults its address-to-DLCI mapping table for the local DLCI that corresponds to the next hop address. Finally, the router places the frames targeted to the remote destination on its identified outgoing local DLCI.

On Cisco routers, dynamic Inverse ARP is enabled by default for all network layer protocols enabled on the physical interface. Packets are not sent out for network layer protocols that are not enabled on the physical interface. For example, no dynamic Inverse ARP resolution is performed for IPX if ipx routing is not enabled globally and there is no active IPX address assigned to the interface. Because dynamic Inverse ARP is enabled by default, no additional Cisco IOS command is required to enable it on an interface.

Example 4-16 shows the output of the show frame-relay map privileged EXEC mode command. The addressto-DLCI mapping table displays useful information. The output of the command shows that the next hop address 172.16.1.2 is dynamically mapped to the local DLCI 102, broadcast is enabled on the interface, and the interface’s status is currently active.

 

NOTE

After enabling Frame Relay on the interface, the Cisco router does not perform Inverse ARP until IP routing is enabled on the router. By default, IP routing is enabled on a Cisco router. If IP routing has been turned off, enable IP routing with the ip routing command in the global configuration mode. After IP routing is enabled, the router performs Inverse ARP and begins populating the address-to-DLCI mapping table with resolved entries.

QUESTION 82

Refer to the exhibit. Which statement describes DL
CI 17?

 

clip_image002

 

A.

DLCI 17 describes the ISDN circuit between R2 and R3.

B.

DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.

C.

DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.

D.

DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.

 

Correct Answer: C

Explanation:

DLCI stands for Data Link Connection Identifier. DLCI values are used on Frame Relay interfaces to distinguish between different virtual circuits. DLCIs have local significance because, the identifier references the point between the local router and the local Frame Relay switch to which the DLCI is connec
ted.

 

 

QUESTION 83

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?

 

clip_image004

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.

 

Correct 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.

 

 

QUESTION 84

At which layer of the OSI model does PPP perform?

 

A.

Layer 2

B.

Layer 3

C.

Layer 4

D.

Layer 5

 

Correct Answer: A

Explanation:

Point-to-Point Protocol (PPP) is a data link protocol commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption (using ECP, RFC 1968), and compression.

 

 

QUESTION 85

What are three reasons that an organization with multiple branch offices and roaming users might implement a Cisco VPN solution instead of point-to-point WAN links? (Choose three.)

 

A.

reduced cost

B.

better throughput

C.

broadband incompatibility

D.

increased security

E.

scalability

F.

reduced latency

 

Correct Answer: ADE

Explanation:

Cisco VPN solutions provide exceptional security through encryption and authentication technologies that protect data in transit from unauthorized access and attacks. A Cisco VPN helps you:

Use highly secure communications, with access rights tailored to individual users Quickly add new sites or users, without significantly expanding your existing infrastructure Improve productivity by extending corporate networks, applications, and collaboration tools Reduce communications costs while increasing flexibility

 

 

 

 

 

QUESTION 86

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.

 

Correct 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.

 

 

QUESTION 87

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.

 

Correct 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.

 

 

QUESTION 88

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.

 

Correct Answer: BC

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.

 

 

QUESTION 89

Which command is used to enable CHAP authentication, with PAP as the fallback method, on a serial interface?

 

A.

Router(config-if)# ppp authentication chap fallback ppp

B.

Router(config-if)# ppp authentication chap pap

C.

Router(config-if)# authentication ppp chap fallback ppp

D.

Router(config-if)# authentication ppp chap pap

 

Correct Answer: B

Explanation:

The command “ppp authentication chap pap” command indicates the CHAP authentication is used first. If it fails or is rejected by other side then uses PAP instead. If you want to use PAP first (then CHAP) you can use the “ppp authentication pap chap” command Reference:

http://www.cisco.com/en/US/docs/ios/12_2/security/configuration/guide/scfathen.html

 

 

QUESTION 90

What command is used to verify the DLCI destination address in a Frame Relay static configuration?

 

A.

show frame-relay pvc

B.

show frame-relay lmi

C.

show frame-relay map

D.

show frame relay end-to-end

 

Correct Answer: C

Explanation:

Cisco Frame Relay Configurations

http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=9

show frame-relay map

The show frame-relay map privileged EXEC mode command shows the contents of the next hop protocol address to DLCI mapping table on the router. The table contains both dynamic mapped and static mapped entries. The below example shows a sample output of the show frame-relay map command.

Router#show frame-relay map

Serial1/2 (up): ip 172.16.1.4 dlci 401(0x191,0x6410), dynamic, broadcast,, status defined, active

Serial1/2 (up): ip 172.16.1.5 dlci 501(0x1F5,0x7C50), dynamic, broadcast,, status defined, active

Serial1/2 (up): ip 172.16.1.2 dlci 301(0x12D,0x48D0), dynamic, broadcast,, status defined, active

 

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