Saturday, July 26, 2008

Welcome back! It's Saturday, July 26, and here are the answers to yesterday's Cisco practice exam questions!

Coming up later today....

1. The answers to my latest CCNA Security practice exam - the answers will be posted on that page, not here in the blog.

2. A new CCNA practice exam, this one on routing protocols.

3. A new set of practice exam questions right here in the blog

.... and anything else I can think of! :)

CCNA Certification:

What command results in the following output?

00:11:37: RIP: received v2 update from on Serial0
00:11:37: via in 1 hops

Answer: That's the output of debug ip rip.

CCENT Certification:

What's the basic purpose of the logging synchronous command?

When the router wants you to know something, it wants you to know right now. If the router sends a message to the console while you're entering a command, by default the router will interrupt your work to show you this message.

In the following example, I opened a Serial interface, which will always result in at least two messages relating to the physical and logical state of the interface. I started typing a sentence immediately after I opened the interface to show you what happens. I've bolded the sentence I was entering.

R1(config)#int s0
R1(config-if)#no shut
R1#so here i am
4d04h: %SYS-5-CONFIG_I: Configured from console by consoletyp
4d04h: %LINK-3-UPDOWN: Interface Serial0, changed state to uping and
4d04h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to upi've been interrupted quite badly!
4d04h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down

This may seen trivial, but when you have a long command entry interrupted by a console message, you'll wonder how to prevent that from happening. (After you stop yelling at the router, that is.)

By configuring the logging synchronous command on the console port, you're telling the router to hold such messages until it detects no input from the keyboard and no other output from the router, such as a show command's output.

R1(config)#line console 0
R1(config-line)#logging ?
synchronous Synchronized message output

CCNA Security Certification / CCNP ISCW Exam:

When configuring a basic firewall in SDM, what are the three options for the preconfigured security levels? Can you create your own custom security levels?

Answer: The options are High, Medium, and Low. In the Basic Firewall Wizard, you cannot create your own custom security levels, but you can do so in the Advanced Wizard.

CCNP Certification / BSCI Exam:

In the following output, describe....

1. Why we would use this command in the first place

2. The meaning of "100"

3. The meaning of "300"

4. The default setting for this particular value, and what we're changing it to.

Answers: By default, EIGRP uses up to 50 percent of a given interface's bandwidth. If you wish to change this default, it can be done with the interface-level command ip bandwidth-percent eigrp.

R1(config)#int s0
R1(config-if)#ip bandwidth-percent eigrp ?
<1-65535> Autonomous system number

R1(config-if)#ip bandwidth-percent eigrp 100 ?
<1-999999> Maximum bandwidth percentage that EIGRP may use

R1(config-if)#ip bandwidth-percent eigrp 100 300

I am showing you this command's values with IOS Help to remind you that you should develop the habit of always taking a few extra seconds to check the values - because in this command, the values look really strange. How in the world can I set EIGRP 100 to use 300% of an interface's bandwidth? And why would I ever do that?

There is always the chance that the actual physical speed of the interface exceeds the logical setting. You could take an interface with a 512 kbps interface and give it a logical setting of 56 kbps.

If you then wanted the line to allow EIGRP to use 168 kbps of the physical bandwidth, you'd set the bandwidth-percent value to 300, which allocates 300% of 56kbps to EIGRP traffic - which is 3 x 56, or 168.

I know it sounds crazy, so here's the proof that you can actually do this:

R3(config)#interface serial0
R3(config-if)#bandwidth 56
R3(config-if)#ip bandwidth-percent eigrp ?
<1-65535> Autonomous system number

R3(config-if)#ip bandwidth-percent eigrp 100 ?
<1-999999> Maximum bandwidth percentage that EIGRP may use

R3(config-if)#ip bandwidth-percent eigrp 100 300

Watch that syntax - the first number is the EIGRP AS; the second number is the bandwidth percentage.

CCNP Certification / BCMSN Exam:

What router redundancy protocol is defined by RFC 2281?

Answer: Our old friend HSRP - the Hot Standby Routing Protocol.

CCNP / ONT Exam:

IntServ uses RSVP, but DiffServ does not. What does DiffServ use in place of RSVP?

Answer: DiffServ uses PHB - Per-Hop Behavior.

New qustions for you later today

Visit my CCNA Security Certification Resource Page for new practice exams and fully-illustrated tutorials!

To your success,

Chris Bryant
CCIE #12933

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