- Which three are types of LCP frames used with PPP? (Choose three.)link-establishment frames*
link-control frames
link-negotiation frames
link-termination frames*
link-acknowledgment frames
link-maintenance frames*
Link-establishment frames establish and configure a link. Link-maintenance frames manage and debug a link. Link-termination frames terminate a link.
- Which command can be used to view the cable type that is attached to a serial interface?Router(config)# show ip interface brief
Router(config)# show ip interface
Router(config)# show interfaces
Router(config)# show controllers*
The show controllers command will allow an administrator to view the type of cable attached to a serial interface such as a V.35 DCE.
- How does PPP interface with different network layer protocols?by using separate NCPs*
by encoding the information field in the PPP frame
by specifying the protocol during link establishment through LCP
by negotiating with the network layer handler
PPP can support multiple network layer protocols, such as IPv4, IPv6, IPX, and AppleTalk. It handles the interface with various network layer protocols via separate NCPs. There is a protocol field in a PPP frame to specify the network layer protocol that is being used. The information field in a PPP frame is the data payload. LCP sets up and terminates a link. It does not check which network layer protocol is used for the data.
- Which address is used in the Address field of a PPP frame?a single byte of binary 10101010
a single byte of binary 11111111*
a single byte of binary 00000000
the IP address of the serial interface
Because PPP is point-to-point, it does not need to assign individual station addresses. The Address field in the frame is a single byte of binary sequence 11111111, the standard broadcast address.
- Which field marks the beginning and end of an HDLC frame?FCS
Data
Control
Flag*
An HDLC frame consists of six or more fields. Two Flag fields are used to mark the beginning and the end of the frame.
- In which situation would the use of PAP be preferable to the use of CHAP?when router resources are limited
when multilink PPP is used
when a network administrator prefers it because of ease of configuration
when plain text passwords are needed to simulate login at the remote host*
There are times when PAP should be used instead of CHAP. When a plain text password is needed to simulate login at a remote host, PAP is preferable, since passwords are not sent in clear text with CHAP.
- When configuring Multilink PPP, where is the IP address for the multilink bundle configured?on a physical serial interface
on a multilink interface*
on a physical Ethernet interface
on a subinterface
When configuring a PPP multilink bundle, the IP address will be configured on the multilink interface, not on the physical interface. This is because the multilink bundle is representing two or more physical interfaces.
- The exhibit displays some partial debug command output:
Refer to the exhibit. Based on the debug command output that is shown, which statement is true of the operation of PPP.
A PPP session was successfully established.*
CHAP authentication failed because of an unknown hostname.
Both PAP and CHAP authentication were attempted.
The debug output is from router R2.
This debug output is from router R1 and shows that a PPP session was successfully established. Success can be verified by the line of output with CDPCP: State is open.
- The exhibit has two boxes. The first box shows the following partial command output:
Refer to the exhibit. A network administrator is configuring the PPP link between the two routers. However, the PPP link cannot be established. Based on the partial output of the show running-config command, what is the cause of the problem?
The usernames do not match.
The passwords should be longer than 8 characters.
The interface IP addresses are in different subnets.
The passwords do not match.*
In PPP authentication, the passwords are case sensitive and must match on both sides.
- Which protocol will terminate the PPP link after the exchange of data is complete?IPXCP
NCP
LCP*
IPCP
LCP terminates a link after exchange of data is complete by exchanging link-termination packets. The link may terminate for various reasons before the data exchange is complete. NCP will only terminate the network layer and NCP link. IPCP and IPXCP are specific network control protocols.
- Which serial 0/0/0 interface state will be shown if no serial cable is attached to the router, but everything else has been correctly configured and turned on?Serial 0/0/0 is up, line protocol is up
Serial 0/0/0 is up (looped)
Serial 0/0/0 is up (disabled)
Serial 0/0/0 is up, line protocol is down
Serial 0/0/0 is down, line protocol is down*
Serial 0/0/0 is administratively down, line protocol is down
The show interfaces privileged exec mode command shows the state of the interfaces, along with much other information that related to them. “Serial 0/0/0 is down, line protocol is down” is displayed if there is no cable connected because there is no Layer 1 or Layer 2 activity going on. The interface has been turned on by the use of the no shutdown command, otherwise the “Serial 0/0/0 is administratively down, line protocol is down” message would be displayed, whether a cable has been connected or not.
- How much total bandwidth is provided by a T1 line?64 kb/s
1.544 Mb/s*
128 b/s
43.736 Mb/s
A T1 line consists of 24 voice channels with 64 kb/s each of bandwidth. This gives a T1 link a total bandwidth of 1.544 Mb/s.
- A network engineer is monitoring an essential, but poor quality, PPP WAN link that periodically shuts down. An examination of the interface configurations shows that the ppp quality 90 command has been issued. What action could the engineer take to reduce the frequency with which the link shuts down?Set the DCE interface to a lower clock rate.
Use the bandwidth command to increase the bandwidth of the link.
Issue the command ppp quality 100.
Issue the command ppp quality 70.*
Issuing the ppp quality 70 command will reduce the link quality threshold before it shuts down from 90% of packets received that were sent, to a drop rate of 70% before shutting down. Setting the threshold to 100% will shut down the link if 100% of packets are not received. Lowering the clock rate will not help a link that is going down. The bandwidth command is used for routing protocol calculations, not link quality.
- A network engineer is troubleshooting the loss of MPEG video viewing quality as MPEG video files cross a PPP WAN link. What could be causing this loss of quality?Link Quality Monitoring was not configured correctly on each interface.
PAP authentication was misconfigured on the link interfaces.
The clock rates configured on each serial interface do not match.
The compress command was used when PPP was configured on the interfaces.*
Using the compress command when configuring PPP on interfaces can reduce the system performance due to a software compression process. The reduced performance may reduce the content delivery quality, especially in the case of audio and video streaming, such as MPEG file streaming. When compressed data files, such as .mpeg, .zip, and .tar files, are carried on the link, using the compress command is not recommended. If PAP is used but misconfigured, the PPP link will not work at all. The clock rate is needed only on the DCE side of a serial link. Configuring Link Quality Monitoring will only monitor the incoming and outgoing link quality. Link Quality Monitoring is not sensitive to which type of content is transmitted.
- Which PPP option can detect links that are in a looped-back condition?Callback
Magic Number*
ACCM
MRU
A Magic Number is randomly generated by PPP at each end of the connection. This number is used by the devices at each end to detect a looped-back condition.
- A network engineer has issued the show interfaces serial 0/0/0 command on a router to examine the open NCPs on a PPP link to another router. The command output displays that the encapsulation is PPP and that the LCP is open. However, the IPV6CP NCP is not shown as open. What does the engineer need to configure to open the IPV6CP NCP on the link?Configure CHAP authentication on each router.
Issue the compress predictor command on each interface on the link.
Configure PPP multilink interfaces on each router.
Configure an IPv6 address on each interface on the link.*
The PPP IPV6CP NCP will open when the interface on each router is configured with an IPv6 address.
- Which three physical layer interfaces support PPP? (Choose three.)synchronous serial*
FastEthernet
Ethernet
GigabitEthernet
asynchronous serial*
HSSI*
PPP can operate across any DTE/DCE interface in either asynchronous or synchronous bit serial mode. The high-speed serial interface (HSSI) developed by Cisco Systems and T3 plus Networking is a DTE/DCE interface that provides high speed connectivity. Asynchronous serial interfaces and synchronous serial interfaces are also DTE/DCE interfaces.
- What are three components of PPP? (Choose three.)authorization
NCP*
HDLC-like framing*
LCP*
parallel communications
support for LAN and WAN
PPP is a WAN protocol to provide serial point-to-point connections. The three main components of HDLC include the Network Control Protocol (NCP), an extensible Link Control Protocol (LCP), and framing similar to HDLC.
- A laptop is connected to an AP and is associated with the connection that is labeled A. The AP is connected to a switch and is associated with the connection that is labeled B. A PC is attached to the switch. The switch is connected to router RTA. The connection of the PC, through the switch, to RTA is associated with the connection that is labeled C. RTA is connected via a serial connection to the ISP and is associated with the connection labeled D.Refer to the exhibit. What type of Layer 2 encapsulation will be used for connection D on the basis of this configuration on a newly installed router:
RtrA(config)# interface serial0/0/0
RtrA(config-if)# ip address 128.107.0.2 255.255.255.252
RtrA(config-if)# no shutdown
PPP
Ethernet
HDLC*
Frame Relay
HDLC is the default encapsulation method on Cisco router serial interfaces. If no other encapsulation is configured, the interface will default to HDLC.
- Which two statements describe a PPP connection between two Cisco routers? (Choose two.)LCP tests the quality of the link.*
LCP manages compression on the link.*
NCP terminates the link when data exchange is complete.
With CHAP authentication, the routers exchange plain text passwords.
Only a single NCP is allowed between the two routers.
PPP uses LCP to perform the functions of establishing, configuring, and testing the data-link connections on the link as well as negotiating encapsulation, authentication, and compression formats.
- Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
Why is the serial link between router R1 and router R2 not operational?The encapsulation in both routers does not match.
The authentication type is not the same in both routers.
The passwords are different in both routers.
In each case the expected username is not the same as the remote router hostname.*
The hostname in one router must be the same as the username in the other router, unless a username is specified with the ppp pap sent-username interface command.
- Question as presented:

Compression, Increases the effective throughput on PPP connections by reducing the amount of data in the frame that must travel across the link.; Multilink, Provides load balancing over the router interfaces. Maximum Recieve Unit, The maximum of the PPP frame. Not used, Helps to ensure a reliable loop-free data ink layer. Authentication Protocol, The two choices are Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP).
- Question as presented:

The first two steps happen at Layers 1 and 2. Once the link is established and configured, link quality can be determined before layer 3 configuration takes place.
- Question as presented:


- Which is an advantage of using PPP on a serial link instead of HDLC?fixed-size frames
higher speed transmission
option for authentication*
option for session establishment
Authentication, multilink, and compression are options on PPP that are advantages over HDLC.