October 23 2009
640-802 Dumps Questions 739 to 741
QUESTION 739
You are about to configure PPP n the interface of a Cisco router. Which authentication methods could you
use? (Select two answer choices)
A. SSL
B. SLIP
C. PAP
D. LAPB
E. CHAP
F. VNP
Answer: CE
Section: IMPLEMENT AND VERIFY WAN LINKS
Explanation/Reference:
Explanation:
Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP)
authenticate the endpoints on either end of a point-to-point serial link.
Chap is the preferred method today because the identifying codes flowing over the link are created using a
MD5 one-way hash, which is more secure that the clear-text passwords sent by PAP.
Reference:
CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press, ISBN 1-58720X) Page 314
QUESTION 740
In a lab, two routers are connected directly together using serial interfaces in a back-to-back configuration. No
external DCE devices are being used. What additional command is needed to bring this link up?
A. serial up
B. clockrate
C. clock rate
D. dce rate
E. dte rate
F. None of the above
Answer: C
Section: IMPLEMENT AND VERIFY WAN LINKS
Explanation/Reference:
Explanation:
The clock rate command (two words), is used to provide clocking on a line where no DCE device is located.
Clocking must be provided by one end of this link. Normally in a point to point HDLC or PPP connection the
clock rate is supplied by the network provider.
Incorrect Answers:
A. This is an invalid command B. This command will not work. The clock rate command must use two words.
D, E: These are invalid commands.
QUESTION 741
An ISDN link can be encapsulated using either PPP or HDLC. What are the advantages of using PPP? (Select
two answer choices)
A. PPP is easier to configure and maintain than HDLC.
B. PPP is consistently implemented among different equipment vendors.
C. PPP will run faster and more efficiently than HDLC on circuit-switched ISDN links.
D. PPP authentication will prevent unauthorized callers from establishing an ISDN circuit.
E. PPP can be routed across public facilities, while HDLC is not routable in circuit-switched networks.
F. PPP supports asynchronous communication.
Answer: BD
Section: IMPLEMENT AND VERIFY WAN LINKS
Explanation/Reference:
Explanation:
PPP has numerous advantages over HDLC. Unlike HDLC which is Cisco proprietary, PPP was designed for
multi-protocol interoperability. Secondly, PPP supports authentication, using either PAP or CHAP. Finally, PPP
supports error correction and the use of bonded multilink circuits.
Incorrect Answers:
A. The default encapsulation is HDLC. PPP must be explicitly configured and there are many more options
available with it, so it is more complicated than HDLC.
C. HDLC is slightly more efficient than PPP.
E. Neither PPP nor HDLC work in public circuit switched environments.
F. Although this is true, it would not be considered an advantage on an ISDN link, as ISDN signaling is not
asynchronous.
Reference: CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press, ISBN 1-58720X) Page 308-
310
