Exam Prep Questions


Question 1

Which of the following is the correct protocol and port combination that is used for BGP connection services?

  • A. TCP, port 69

  • B. UDP, port 23

  • C. TCP, port 179

  • D. UDP, port 179

A1:

Answer C is correct. BGP uses TCP port 179 as its transport Layer 4 mechanism for reliable data exchange and loop- avoidance . Answer A is incorrect because TCP port 69 is for Trivial File Transfer Protocol (TFTP). Answer B is incorrect because BGP uses TCP and port 23 is for Telnet services. Answer D is incorrect because although the port number is correct, BGP uses TCP for its update messages.

Question 2

Which of the following command sets represents a valid way to configure a BGP router with an external peer?

  • A. router bgp 65520 neighbor 10.10.10.1 remote-as 65510

  • B. router bgp 65550 neighbor 10.10.10.1 remote-as 65560

  • C. router bgp 65520 neighbor 10.10.10.1 as 65510

  • D. ip bgp 65520 neighbor 10.10.10.1 remote-as 65510

A2:

Answer A is correct. The router bgp command starts the process, and the neighbor remote-as combination creates a peer relationship with the BGP neighbor. Answer B is a trick because the AS numbers are invalid. The ASN must be between 1 and 65,535, a 16-bit number. Answer C is incorrect because the remote-as command was not used. Answer D is incorrect because the command to start the process is router bgp , not ip bgp .

Question 3

In which of the following BGP scenarios would it be acceptable to implement static routes? (Choose 2.)

  • A. Your router does not have enough memory or processing power to handle the BGP update messages and large routing tables.

  • B. You are implementing a multihoming solution in an enterprise environment to connect to more than one ISP.

  • C. You have only a single connection to another autonomous system or the Internet.

  • D. The inbound and outbound traffic flow of your network must be highly controlled through route policy and route selection.

A3:

Answers A and C are correct. Static routes would be appropriate to use when your router has inadequate resources to handle the BGP update messages and large routing tables, when you have only a single connection to another autonomous system or the Internet, when you have no need to implement routing policy, and when you have low bandwidth channels between the autonomous systems. Answers B and D are incorrect because these are examples of situations in which you should strongly consider BGP routing instead of static routing.

Question 4

Which one of the following types of BGP attributes might not be recognized nor expected because it is destined for some private BGP network but will be marked as "partial" and sent on its way to its peers untouched?

  • A. Well-known, mandatory

  • B. Well-known, discretionary

  • C. Optional, transitive

  • D. Optional, non-transitive

A4:

Answer C is correct. A BGP router might not recognize an optional transitive attribute and it is not expected to because it is headed for some private BGP network. If the BGP speaker fails to recognize an optional transitive attribute, it marks it as a "partial" message and continues to propagate it to its peers untouched (transitive). Answer A is incorrect because well-known mandatory attributes must appear in all BGP update messages and are recognized by all compliant BGP implementations . Answer B is incorrect because although a well-known, discretionary attribute does not have to exist in a route description, it doesn't meet the other stated criteria. Answer D is incorrect because a non-compliant router must drop an optional non-transitive attribute.

Question 5

Which of the following displays the proper order of preference for the MED, Local-preference, and Weight attributes?

  • A. Local preference, MED, Weight

  • B. Weight, MED, Local preference

  • C. MED, Local preference, Weight

  • D. Weight, Local preference, MED

A5:

Answer D is correct. The correct preference order is Weight, Local preference, then MED. The route with the highest Weight attribute is preferred. If multiple routes have the same Weight, then the route with the highest Local preference attribute is used. MED is farther down the chain of preferences as sent from other ASs.

Question 6

You are not passing traffic from another AS through your AS and all your AS routers are running BGP. What command could you run to carry fewer routes in your IGP and allow BGP to converge more quickly?

  • A. no auto-summary

  • B. no synchronization

  • C. disable auto-summary

  • D. disable synchronization

A6:

Answer B is correct. You will use the BGP configuration command no synchronization to disable the synchronization of routing information between the IGPs and BGP within a fully meshed, non-transit AS. Now your router can use and advertise a route learned by IBGP to an EBGP peer before the routes are learned within the IGP as well as improve convergence. Answer A is incorrect because no auto-summary disables the automatic route summarization for EIGRP. Answer C is incorrect because it is neither a valid command nor applicable to BGP. Answer D is incorrect because you use the no command, not disable , to turn off BGP synchronization.

Question 7

Which one of the following is not a valid BGP message type?

  • A. Notification

  • B. Keepalive

  • C. Update

  • D. Hello

A7:

Answer D is correct. The Hello protocol message is not one of the BGP message types. Answers A, B, and D are incorrect because they are actually valid message types. BGP has four different types of messages that are exchanged between BGP routers: open, keepalive, update, and notification. The open message is the first message sent after the TCP connection is established. The keepalive message confirms that connections are active or established and is exchanged between peers so that hold times do not expire. The update message is generated if a change occurs and has information on a single path only. Notification messages are sent to alert BGP peers about detected errors.

Question 8

Which of the following is a valid BGP Origin attribute value that displays in the BGP table as a question mark (?) because the NLRI is unknown?

  • A. UNKNOWN

  • B. INCOMPLETE

  • C. NONTRANSITIVE

  • D. MISSING

A8:

Answer B is correct. The INCOMPLETE Origin value shows up as a question mark in the BGP table because the NLRI is unknown or is learned by some other method such as a redistributed static route into BGP where the origin of the route is incomplete. Answer A is incorrect because UNKNOWN is not a valid Origin attribute value. Answer C is incorrect because NONTRANSITIVE is not a valid Origin attribute value. Answer D is incorrect because MISSING is not a valid Origin attribute value.

Question 9

Which of the following attributes is a well-known mandatory attribute with BGP type code 3 and represents the next IP address that will be used to reach a particular destination?

  • A. Origin

  • B. Next-hop

  • C. AS-path

  • D. Local preference

  • E. Aggregator

A9:

Answer B is correct. The Next-hop attribute is BGP type code 3 and is a well-known mandatory attribute. The BGP next hop attribute is simply the next hop IP address that is going to be used to reach a certain destination. Answer A is incorrect because the Origin attribute is BGP type code 1 and is a well-known, mandatory attribute. Answer C is incorrect because the AS-path attribute is BGP type code 2 and is a well-known mandatory attribute. Answer D is incorrect because the Local preference attribute is BGP type code 5 and is a well-known discretionary attribute. Answer E is incorrect because the Atomic aggregate value is BGP type code 6. It is a well-known discretionary attribute that notifies BGP routers of policy routing choices made when there are overlapping routes.

Question 10

Which one of the following commands can invoke a console display of BGP update messages?

  • A. debug ip bgp

  • B. show ip bgp summary

  • D. show ip bgp neighbors

  • E. show ip bgp

A10:

Answer A is correct. The debug ip bgp updates command invokes a console display of BGP update messages. Answer B is incorrect because the show ip bgp summary command displays the status of all BGP connections. Answer C is incorrect because the show ip bgp neighbors command displays details about TCP and BGP neighbor connections. Answer D is incorrect because the show ip bgp command shows the BGP routing table.



Cisco BSCI Exam Cram 2 (Exam Cram 642-801)
CCNP BSCI Exam Cram 2 (Exam Cram 642-801)
ISBN: 0789730170
EAN: 2147483647
Year: 2003
Pages: 170

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net