Monday, July 28, 2008

Welcome back! It's Monday, July 28, and here are the answers to yesterday's Cisco practice exam questions.

Be sure to read today's other blog posts for links to the answers to my latest CCNA Security exam, a new CCNA / CCENT practice exam, and other surprises!

CCNA Certification:

Examine the following output and tell me what defaults have been changed.

R1#show ip protocols
Routing Protocol is "rip"
Sending updates every 30 seconds
Invalid after 180 seconds, hold down 180, flushed after 240

Answer: None of the RIP default timers have been changed.

CCENT Certification:

At which layer of the OSI model do the following protocols run?


Answer: They all run at the Transport layer - Layer 7 - of the OSI model.

CCNA Security Certification / CCNP ISCW Exam:

You're working in SDM to create a VPN. What service must be running on the router to do so? (Hint: If the router isn't already running it, SDM will prompt you to activate it.)

Answer: AAA must be running. As shown here, the Launch Easy VPN Server Wizard button will not even be enabled if AAA is not running. Note that SDM has an Enable AAA option on the right-hand side of the window.

Clicking Enable AAA brings up the following prompt:

Answering Yes will enable AAA on the router and the Launch Easy VPN Server Wizard button will then be enabled.

CCNP Certification / BSCI Exam:

When you enter the command shown below, what unusual characteristic will the route to have that no other route in the EIGRP routing table will have?

R1(config)#interface serial0
R1(config-if)#ip summary-address eigrp 100

Answer: The exit interface for the summary route will be Null0, as shown in this routing table excerpt:

R1#show ip route

<> is variably subnetted, 8 subnets, 2 masks
C is directly connected, Loopback4
C is directly connected, Loopback5
C is directly connected, Loopback6
C is directly connected, Loopback7
D is a summary, 00:07:32, Null0
C is directly connected, Loopback0
C is directly connected, Loopback2
C is directly connected, Loopback3

On R1, the summary route is seen as a route to Null0, which is basically a route to the trash can. If a packet comes into this router that doesn't match one of the seven more-specific routes, it will be "black-holed" - dropped by the router.

This default behavior of EIGRP route summarization helps to prevent routing loops.

This null route will only be seen on the router performing the manual summarization.

CCNP Certification / BCMSN Exam:

What two protocols are used to negotiate Etherchannel parameters between switches?

Answer: LAPB and PAgP.

CCNP / ONT Exam:

At what layer of the Cisco Hierarchical Switching Model should packet classification not take place?

Answer: You should perform packet classification as close to the end user as possible - and never classify packets at the Core layer!

I'll have new questions for you later today here on the blog and on the main website, and in the meantime, visit my new CCNA Security Certification Resource Page for practice exams and fully-illustrated tutorials - you'll be glad you did!

To your success,

Chris Bryant
CCIE #12933

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