Friday, February 06, 2009

Here are the answers to the Cisco practice exam questions posted on Wednesday!

CCNA And CCENT Certification:

Identify the OSI Model layers described below. (Answers have been added to each choice.)

A. Routing takes place here - Network

B. Switching takes place here - Data Link

C. UDP and TCP operate here - Transport

D. Telnet operates at this layer - Application

E. Data is placed into segments at this layer - Transport

F. Data is carried in packets at this layer - Network

CCNA Security:

There's a DoS attack, and then there's a DDoS attack. Besides the spelling, what's the major difference between the two?

Answer: The extra "D" in DDoS stands for Distributed, and this means the Denial of Service attack's source is a multiple number of computers, rather than a single source.

CCNP Certification / BSCI Exam:

What's the basic difference between a stub area and a total strub area?

Answer: OSPF routers in stub areas can have routes with these routing table codes:

O - routes to destinations inside the area

O IA - routes to destinations in other OSPF areasO *IA - a default inter-area route used to reach external destinations

OSPF routers in total stub areas can have routes with these routing table codes:

O - routes to destinations inside the area

O *IA - a single default route used to reach destinations in other OSPF areas AND external destinations.

CCNP Certification / BCMSN Exam:

Giving a typical example of when each would be used, name the major operational difference between Backbonefast and Uplinkfast.

Answer: Uplinkfast is pretty much Portfast for wiring closets.

The ports that a switch could potentially use to reach the root switch are collectively referred to as an uplink group. The uplink group includes the ports in forwarding and blocking mode. If the forwarding port in the uplink group sees that the link has gone down, another port in the uplink group will be transitioned from blocking to forwarding immediately.

Uplinkfast and Portfast are great, but they've got limitations on when they can and should be run. You definitely can't run either one in a network backbone, but the Cisco-proprietary feature Backbonefast can be used to help recover from indirect link failures.

The key word there is indirect. If a core switch detects an indirect link failure - a failure of a link that is not directly connected to the core switch in question - Backbonefast goes into action.

This indirect link failure is detected when an inferior BPDU is received.

Your answer may have been shorter. :)

CCNP Certification / ISCW Exam:

Which of the following would you *not* configure from the Additional Tasks section of SDM?




D. Security Audit

E. One-Step Lockdown

Answer: B, D, E. DNS and DHCP are both found in the Additional Tasks section.

CCNP Certification / ONT Exam:

What are the four major steps for taking an analog signal and converting it to digital?

Analog-to-digital steps:

Sample the analog signal

Quantize that sample

Encode the signal

Compress the samples (optional, helps to conserve bandwidth)

New questions posted later today!

To your success,

Chris Bryant
CCIE #12933

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