85 Questions
What are point-to-point connections used for networking (Choose two)? (A) Connecting LANs to cellular networks. (B) Connecting LANs to service provider WANs. (C) Connecting LANs to satellite networks. (D) Connecting LANs to public Wi-Fi networks. (E) connect LAN segments within an enterprise network.
B,E
What type of sites can a point-to-point link connect, as mentioned in the text?
Two Geographically distant sites (corporate office in New York and a regional office in London)
How can serial connection bandwidths accomodate the need for faster transmission?
By incrementally increasing the bandwidth
On each WAN connection, data is encapsulated into frames before crossing the WAN link.
True
What happens to data on each WAN connection before crossing the WAN link?
Data is encapsulated into frames
Which encapsulation type is the default on point-to-point connections, dedicated links, and circuit-switched connections when the link uses two Cisco devices?
HDLC
What type of framing structure does HDLC define that allows for flow control and error control through acknowledgments?
Layer 2 framing
How does HDLC mark the beginning and the end of each frame?
Using frame delimiter or flag
What type of field do Cisco HDLC frames contain for identifying the ____ being encapsulated?
Network protocol
What are the two steps to re-enable HDLC encapsulation on a SERIAL interface?
Enter the interface configuration mode and then enter the encapsulation hdlc command
What information does the "show controllers" diagnostic tool command provide when troubleshooting serial lines?
State of the interface channels and if cable is attached to the interface.
What are the possible states that the "show interfaces serial" command can return? (A) Serial x is up, line protocol is up. (B) Serial x is down, line protocol is down. (C) Serial x is running, line protocol is down. (D) Serial x is up, line protocol is down. (E) Serial x is up, line protocol is up (looped). (F) Serial x is Active with looped protocol, Inactive with disabled protocol. (I) Serial x is up, line protocol is down (disabled). (L) Serial x is administratively down, line protocol is down. (M) Serial x is Active and connected, Inactive and disconnected . choose 6 answers:
A, B, D, E, I, L
When connecting a Cisco router to a non-Cisco router, which encapsulation protocol can be used?
PPP
Choose two PPP advantages: (A) PPP supports PAP and CHAP authentication. (B) PPP uses an Error Correction feature to detect erroes if the link is failed. (C) PPP uses link quality management feature to monitor the quality if the link, of too many errors are detected, PPP takes the link down. (D) PPP uses Flow Control feature to monitor the quality of the link, if too many errors are detected, PPP takes the link down.
A, C
PPP and OSI share the same physical layer, But What functions are distributed differently by PPP compared to OSI?
Link Control Protocol (LCP) and Network Control Protocols (NCPs)
What is the absolute requirement imposed by PPP for the circuit used?
Full-duplex circuit
A full-duplex circuit can either be __ or ___?
Switched or dedicated
A full-duplex circuit can operate in an _____ or ______ bit-serial mode?
asynchronous or synchronous
Which layers of the OSI model does PPP primarily operate at by LCP and NCPs (choose two)?
Data Link Layer and Network Layer
What is the primary function of the Link Control Protocol (LCP) in PPP?
Establishing the point-to-point link
what other function does LCP perform in PPP?
Negotiates and sets up control options on the WAN data link which are handled by the NCPs.
After the link is established, Why does PPP use LCP?
to automatically agree on Encapsulation formats such as authentication, compression, and error detection.
What does PPP permits to operate on the same communications link?
Multiple network layer protocols on the same link
How does PPP handle every network layer protocol ?
PPP uses a separate NCP for each network layer protocol
What is the role of each NCP in PPP?
Managing the specific needs required by its respective network layer protocols
How many fields are there in a PPP frame?
Six fields
Which of the following are the 3 classes of LCP frames are used in LCP operation to accomplish the work of each LCP phases? (Select all that apply) (A) Link-establishment frames establish and configure a link. (B) Link-maintenance frames manage and debug a link. (C) Link-termination frames terminate a link. (D) Data-transmission frames for transferring user data. (E) Error-correction frames for handling transmission errors.
A, B, C
Which 3 of the following phases are involved in establishing a PPP session? (Select all that apply) (A) Phase 1: Link establishment and configuration negotiation. (B) Phase 3: Error correction and retransmission. (C) Phase 3: Network layer protocol configuration negotiation. (D) Phase 1: Data transmission and reception. (E) Phase 2: Link quality determination (optional)
A, E , C
Which of the following optional functions can be configured in PPP? (Select all that apply) (A) Encryption. (B) Framing. (C) Authentication. (D) Compression. (E) Multilink.
C, D, E
After LCP has established the link, the routers exchange IPCP messages for which of the following purposes? (Select all that apply) (A) Compression. (B) Encryption. (C) IPv4-Address. (D) Error Correction. (E) Quality of Service (QoS).
A, C
Which of the following options may be included in PPP as part of LCP (Link Control Protocol)? (Select all that apply) (A) Encryption. (B) Framing. (C) Authentication. (D) Compression. (E) Error detection. (F) PPP Callback. (G) Multilink.
C, D, E, F, G
To set PPP as the encapsulation method used by a serial interface, use the encapsulation ppp interface configuration command.
True
Point-to-point software compression on serial interfaces can be configured after enabling PPP encapsulation on a serial interface by using which command?
compress
The ppp quality percentage command ensures that the link meets the quality requirement set; otherwise, the link closes down.
What does the "ppp quality percentage" command do in PPP configuration
Ensures link quality by closing down the link if quality requirements are not met by the link
What does MPPP do to packets?
Fragmentation of packets to be fragments that are sent over mulitple PPP links to the same remote addresss
When configuring MPPP, what are the two steps required for setup? (A) Assign interfaces to the multilink bundle. Choose to answers (B) Configure QoS settings. (C) Create a multilink bundle. (D) Set up encryption for data transfer.
C, A
The "show interfaces serial" command is used to verify the proper configuration of HDLC or PPP encapsulation.
True
According to RFC 1334, "PPP Authentication Protocols," defines two protocols for authentication. What are the two authentication protocols defined in RFC 1334?
PAP and CHAP
Which of the following statements accurately describes the Password Authentication Protocol (PAP)? A) PAP uses encryption to secure the username and password transmission?
PAP sends the username and password in plaintext without encryption.
Which of the following statements accurately describes the Password Authentication Protocol (PAP)?
PAP is a very basic two-way process sends the username and password in plaintext without encryption.
CHAP is more secure than PAP as it involves a three-way exchange of a shared secret.
True
How can you specify the order in which the CHAP or PAP protocols are requested on the interface in Cisco IOS?
Use the "ppp authentication" interface configuration command
To disable authentication protocols on a Cisco IOS interface, which command should be used?
no ppp authentication
In a Point-to-Point Protocol PPP setup with PAP, what must match between the routers for successful authentication?
Username and password specified in the "username name password password" command
Which of the following statements accurately describe the characteristics of the Password Authentication Protocol (PAP)? (A) Not a strong protocol. (B) Uses a two-way handshake. (C) PAP is considered a robust and secure authentication protocol. (D) PAP sends username and password in encrypted form. (E) Username/Password sent in clear text. (F) Remote node in control of attempts. (Choose four answers)
A, B, E, F
Which of the following statements accurately describes the behavior of the Username/Password pair in the Password Authentication Protocol (PAP)?
The Username/Password pair is sent across the link repeatedly until authentication is acknowledged or the link is terminated.
Rtr(config)#username remote-host password remote-password, This commaned needs to match the ppp pap sent-username and password on the remote host. (true or false) ? EXPLANATION in page 20^
True
What is the outcome when routers with the specified username/password combinations are received and validated in the context of PPP PAP sent-username password?
The routers will be allowed to connect and establish a connection.
Rtr(config-if)#ppp pap sent-username local-host-username password local-host-password, The passwords have to be the same on the remote and the local routers. (True or False). EXPLANATION in page 20^
False
Rtr(config-if)#ppp pap sent-username local-host-username password local-host-password, the password should not be the same as the enable-secret password. (True or False). EXPLANATION in page 20^
True
Which of the following statements accurately describes the Challenge Handshake Authentication Protocol (CHAP)? (A) Challenge/Response sequence repeated at random periods during the connect. (B) Challenge/Response messages uses MD5 hashing on random values and the password. (C) utilizes SHA-1 hashing for generating challenge/response messages. (D) uses a three-way handshake. (E) The preferred authentication protocol. (F) uses a two-way handshake for authentication. Choose four answers
A, B, D, E
How does (CHAP) provides protection against playback attacks?
By using a variable and hashed challenge value that is unique and unpredictable
What is the purpose of using repeated challenges in CHAP?
to limit the time of exposure to any single attack
How does CHAP differ from PAP regarding the control of frequency and timing of the challenges?
CHAP gives control to the local router or a third-party authentication server.
What is the purpose of the "debug ppp authentication" command in a router configuration?
Display the authentication exchange sequence
What is the purpose of the "debug ppp chap" command in a router configuration?
Display CHAP packet exchanges
What is the purpose of the "debug ppp error" command in a router configuration?
Display protocol errors and error statistics
What is the purpose of the "debug ppp negotiation" command in a router configuration?
Display packets during connection establishment.
What is the purpose of the "debug ppp packet" command in a router configuration?
Display packets being sent and received.
debug ppp "argument" is used with arguments like debug ppp chap ?
True
What type of transmission sends one bit at a time over a single channel?
Serial transmission
Which statement is true regarding serial communications?
A serial port is bidirectional
What is a requirement for synchronous serial communications?
A clocking signal is required
Which statement is true regarding point-to-point links and their importance for certain protocols?
Constant availability is important for some protocols, such as VoIP, to ensure reliable communication.
PPP links is more expensive than shared services?
True
What technology does SONET use for efficient use of bandwidth?
STDM
(may be not an important qn) In the United States, what are the standardized specifications for SONET transmission rates?
OC
Which carrier system is used in North America for the bandwidth hierarchy?
T-carrier
Which carrier system is used in Europe for the bandwidth hierarchy?
E-carrier
What is the fundamental line speed in North America's T-carrier system?
64 kbps(DS0)
why are Multiple DS0s are bundled together ?
higher line speed
In a network setup, which device is typically considered the DTE (Data Terminal Equipment)?
Router(CPE)
In a network setup, which device is typically considered the DCE (Data Terminal Equipment) choose two? (A) Modem. (B) Router(CPE). (C) CSU/DSU. (D) Switch.
A, C
What is the default encapsulation method used on Cisco synchronous serial lines?
Cisco HDLC
What is Cisco HDLC primarily used for in networking?
Multiprotocol support
What type of protocol is Cisco HDLC?
Bit-oriented synchronous data link layer protocol
When would you typically use Synchronous PPP in a networking environment? (A) To connect to non-Cisco devices. (B) For wireless communication. (C) To bundle links for shared use. (D) For encryption purposes. (E) monitor link quality. (F) provide authentication.
A , C, E, F
What protocol does PPP use for encapsulating datagrams?
HDLC
What is the primary function of LCP in the PPP protocol?
Establishing, configuring, testing, and terminating the data link connection
Which authentication protocols can LCP optionally use to authenticate a peer in PPP?
PAP and CHAP
What is the purpose of the Network Control Protocols (NCPs) in the PPP protocol?
To support multiple network layer protocols simultaneously
How does Multilink PPP spread traffic across bundled links?
By fragmenting packets and simultaneously sending fragments over multiple links to same remote address, where they are reassembled
Which authentication protocols does PPP optionally support for authentication?
PAP, CHAP, or both PAP and CHAP
How does the Password Authentication Protocol (PAP) send authentication data?
In plaintext
How does the Challenge-Handshake Authentication Protocol (CHAP) protect against playback attacks? Choose three (A) By using encryption. (B) By using compression. (C) By using a 3-way handshake. (D) By using periodic challenge messaging. (E) By using one-way hash.
C, D, E
Study Notes
Point-to-Point Connections
- Point-to-point connections are used for:
- Connecting LANs to service provider WANs
- Connecting LAN segments within an enterprise network
WAN Connections
- On each WAN connection, data is encapsulated into frames before crossing the WAN link
- Frames are encapsulated before crossing the WAN link
HDLC
- HDLC (High-Level Data Link Control) is a framing structure that defines flow control and error control through acknowledgments
- HDLC marks the beginning and end of each frame
- Cisco HDLC frames contain a field for identifying the protocol being encapsulated
- HDLC can be re-enabled on a SERIAL interface by:
- Configuring the serial interface
- Re-enabling HDLC encapsulation
Serial Connections
- The "show controllers" diagnostic tool command provides information for troubleshooting serial lines
- The "show interfaces serial" command can return the following states:
- Serial x is up, line protocol is up
- Serial x is down, line protocol is down
- Serial x is up, line protocol is down (disabled)
- Serial x is administratively down, line protocol is down
PPP (Point-to-Point Protocol)
- PPP is a protocol that can be used to connect a Cisco router to a non-Cisco router
- PPP advantages:
- Supports PAP and CHAP authentication
- Uses link quality management to monitor the quality of the link
- PPP uses an Error Correction feature to detect errors if the link fails
- PPP functions are distributed differently compared to OSI
- A full-duplex circuit can operate in a half-duplex or full-duplex mode
- PPP primarily operates at the physical and data link layers of the OSI model
- LCP (Link Control Protocol) is used to establish, configure, and manage the connection
- NCPs (Network Control Protocols) are used to configure and manage network layer protocols
- PPP permits multiple network layer protocols to operate on the same communications link
- PPP handles each network layer protocol separately
LCP (Link Control Protocol)
- LCP is used to establish, configure, and manage the connection
- LCP performs the following functions:
- Establishes and configures a link
- Manages and debugs a link
- Terminates a link
- LCP frames are used in LCP operation to accomplish the work of each LCP phase:
- Link-establishment frames establish and configure a link
- Link-maintenance frames manage and debug a link
- Link-termination frames terminate a link
- PPP uses LCP to establish and configure a link
NCP (Network Control Protocol)
- NCP is used to configure and manage network layer protocols
- Each NCP is responsible for managing a specific network layer protocol
- NCPs are used to configure and manage network layer protocols
PPP Frames
- A PPP frame consists of:
- A header
- An information field
- An FCS (Frame Check Sequence)
- PPP frames are used to transmit data
- PPP frames are used to manage the connection
Authentication Protocols
- PPP supports the following authentication protocols:
- PAP (Password Authentication Protocol)
- CHAP (Challenge-Handshake Authentication Protocol)
- PAP sends username and password in clear text
- CHAP is more secure than PAP as it involves a three-way exchange of a shared secret
- CHAP provides protection against playback attacks
- CHAP uses a three-way handshake
Multilink PPP (MPPP)
- MPPP is used to bundle multiple links together
- MPPP is used to increase bandwidth
- MPPP can be configured by:
- Assigning interfaces to the multilink bundle
- Configuring QoS settings
- MPPP spreads traffic across bundled links
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
