Cisco CCNA answers: CCNA 4

1.Which authentication protocol can be spoofed to allow playback attacks?

MD5

CHAP

PAP

NCP

2.Refer to the exhibit. Which two statements are true about this configuration? (Choose two.)

Authentication will fail between these routers.

Each router authenticates its neighbor against the username and password that are configured in

the local database.

The default encapsulation type is configured on these routers.

NCP negotiates for IP to use predictor compression.

If there is more than a 20% error rate on the line, then LCP will take the line down.

3.Which two options can LCP negotiate? (Choose two.)

link quality

authentication

dynamic flow control

compression and network layer address for IP

connection-oriented or connectionless communication methods

4.Which statement describes parallel data communications?

Digital data is broken into 8-bit chunks (bytes) and transmitted from one entity to another bit by bit.

Digital data that is transmitted over a parallel connection is not affected by clock skew or crosstalk.

Digital data is transmitted from one entity to another via the use of a bus that consists of multiple wires, each carrying one bit of the data sample.

Digital data is transmitted via the use of two loops of wire, one in each direction.

5.Refer to the exhibit. On the basis of the show interface Serial0/0/0 output, how many NCP sessions have established?

one

two

three

four

6.Which serial communications DTE/DCE interface standard is used to provide high-speed connectivity of 52 Mbps between LANs and is found on many high-end Cisco routers?

EIA/TIA 232 (RS-232)

ITU V.35

HSSI

EIA/TIA 422 (RS-422)

EIA/TIA 423 (RS-423)

7. Which three statements are correct about HDLC encapsulation? (Choose three.)

HDLC supports PAP and CHAP authentication.-ppp

HDLC implementation in Cisco routers is proprietary.

HDLC specifies a data encapsulation method on synchronous serial links using frame characters checksums

HDLC is the default serial interface encapsulation on Cisco routers.

HDLC and PPP are compatible.

HDLC does not support CDP.

8.Which three statements correctly describe PPP authentication? (Choose three.)

PAP sends passwords in clear text.

PAP uses a 3-way handshake to establish a link.-

PAP provides protection from repeated trial-and-error attacks.-

CHAP uses a 2-way handshake to establish a link.-

CHAP uses a challenge/response that is based on the MD5 hash algorithm.

CHAP uses repeated challenges for verification.

9.Refer to the exhibit. Which two items were negotiated during the PPP session shown in the debug output? (Choose two.)

Challenge Handshake Authentication Protocol

Password Authentication Protocol

compression

link quality

error detection

10.Which three statements are true regarding LCP? (Choose three.)

It is responsible for negotiating link establishment.

It negotiates options for Layer 3 protocols running over PPP.

It uses MD5 encryption while negotiating link establishment parameters.

It terminates the link upon user request or the expiration of an inactivity timer.

It can test the link to determine if link quality is sufficient to bring up the link.

It monitors the link for congestion and dynamically adjusts the acceptable window size.

11.Refer to the exhibit. What statement is true regarding the output shown?

LCP is in the process of negotiating a link.

LCP and NCP are waiting for CHAP authentication to complete.

LCP negotiation has been successful, but NCP negotiation is in progress.

Data is able to flow across this link.

12.What does the demarcation point represent in data communication physical circuits?

DTE/DCE interface on the device connecting to the Internet

location of the firewall or router

physical point at which the public network ends and the private customer network begins

tag assigned to the physical block where a cross-connect occurs

13.Which two statements are true regarding time-division multiplexing (TDM)? (Choose two.)

It allows information from multiple channels to be allocated bandwidth on a multiple wires.

Multiple sources can transmit over a single channel.

Original data streams must be reconstructed at the destination.

TDM relies on Layer 3 protocols to operate.

TDM methods vary depending on the Layer 2 protocol used.

14.Refer to the exhibit. What statement is true regarding the output shown?

NCP has successfully negotiated.

The PAP passwords did not match, so the routers are trying CHAP authentication.

One router has suggested PAP authentication, and the other has accepted authentication but suggested CHAP authentication.

One router can only use PAP authentication while the other router can only use CHAP, so the connection

has been rejected.

15.Refer to the exhibit. Which two statements are true regarding the output shown? (Choose two.)

LCP negotiation has been successful.

The router has agreed on IP parameters.

The router is negotiating IP compression options.

The router is requesting an IP address from its peer.

The router has accepted IP but not the suggested IP options.

16.What function do Network Control Protocols provide for a PPP connection?

to establish and terminate data links

error detection

to manage network congestion and to allow quality testing of the link

to allow multiple Layer 3 protocols to operate over the same physical link

to provide authentication capabilities to PPP

17.Refer to the exhibit. Which series of statements accurately describes the PPP link establishment process for these routers?

LCP negotiates the authentication option

LCP tests link quality

PAP authentication