quiz 3.txt

这是 ssd8 exam1 的选择题 比较全 感兴趣的 朋友 可以 参考一下

 1. 
 A corporate information systems manager is interested in collecting statistics on the frequency of computer failures within the organization. Most failures result in an automatic reboot, so the failed computer is typically back on the network in less than a minute. The corporate network connects 1,500 computers in far-flung locations to which the average latency of a packet is 40 milliseconds. The manager asks you to write a tool that will collect the times at which failures occurred in which computers. She wants it by tomorrow, so the tool will have to be simple. On which protocol will you base your implementation?  
 

  (a) SNMP
 (b) ICMP (ping)
 (c) PLM
 (d) TCP  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.6 of the course notes.  
 

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 2. 
 The IP address space is organized in a hierarchy 
to make the routing task more scalable 
to decrease inefficient fragmentation of the address space 
to give institutions managing local-area networks autonomous control over the assignment of addresses to computers 
 
 

  (a) I and III only
 (b) I only
 (c) none
 (d) II only  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.3 of the course notes.  
 

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 3. 
 Using the Domain Name System, we can find 
that 204.194.30.130 is the IP address of www.example.com 
that ns.watson.ibm.com knows how to handle email for all IBM employees 
that a datagram for an IBM address in India will be routed through an Internet IBM router named ibm-gw.customer.ibm.net in New York 
 
 

  (a) II and III only
 (b) I and II only
 (c) I only
 (d) I, II, and III  

 Correct answer is  (b)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.5 of the course notes.  
 

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 4. 
 The network interface card of a Web server that you manage has developed sporadic problems. You measure the packet loss rate from your desktop computer and immediately decide to replace the network card. After this simple operation, the Web server successfully rejoins the network, as confirmed by your officemate using her desktop computer. You eagerly go to your desktop to measure the improvement, but find instead that the Web server is not responding to any of your packets. What is your diagnosis?  
 

  (a) Your desktop computer is still trying to contact the server's old network card.
 (b) The Domain Name System (DNS) has not yet updated its entry for the Web server.
 (c) Your desktop computer's network card does not work.
 (d) The new network card does not work.  

 Correct answer is  (a)  

 Your score on this question is: 0.00  

 Feedback: 
   See section 1.3.5 of the course notes.
   (b) The server's IP address has not changed, so its DNS entry need not be updated.  
 

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 5. 
 The class B IP network 128.2.x.x has been assigned to Carnegie Mellon University. To relieve congestion in its internal LAN, Carnegie Mellon has decided to subnet this IP network. This will have which of the following consequences? 
The configuration of the subnets will have to be announced to routers all over the world by notifying NIC and/or IANA. 
A computer may need to change its IP address when moved from one office to another. 
Some bridges, hubs, or switches will need to be replaced with routers. 
 
 

  (a) I, II, and III
 (b) I and III only
 (c) II and III only
 (d) III only  

 Correct answer is  (c)  

 Your score on this question is: 0.00  

 Feedback: 
   See section 1.3.3 of the course notes.  
 

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 6. 
 Which of the following protocols are essential to the existence of the Traceroute tool? 
IP 
ICMP 
TCP 
 
 

  (a) I only
 (b) I and II only
 (c) II only
 (d) II and III only  

 Correct answer is  (b)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.7 of the course notes.  
 

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 7. 
 After coming back from a vacation, you are eager to read your mail. You have several email accounts. One of them is served from hotmail.com, so you open up your browser and try to go to www.hotmail.com. Unfortunately, www.hotmail.com is down at the moment. 
Because of this, which of the following packet types have traversed your ISP's router?

ARP 
DNS 
IP 
 
 

  (a) none
 (b) II and III only
 (c) I, II, and III
 (d) II only  

 Correct answer is  (b)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.5 of the course notes.  
 

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 8. 
 The Internet Protocol (IP) 
is the only network-layer protocol 
is required of hosts on the Internet 
is the body of standard protocols in use on the Internet 
 
 

  (a) I only
 (b) II and III only
 (c) I and II only
 (d) II only  

 Correct answer is  (d)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.1 of the course notes.  
 

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 9. 
 The following Java declaration 
InetAddress addr = InetAddress.getbyName("www.example.com");

will fail when  
 

  (a) www.example.com does not respond to ARP requests
 (b) a route to www.example.com is not available
 (c) www.example.com is down
 (d) all known DNS servers are down  

 Correct answer is  (d)  

 Your score on this question is: 10.00  

 Feedback: 
   See Chapter 10 of the yellow book. See section 1.3.5 of the course notes.  
 

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 10. 
 A difference between routers and switches is that  
 

  (a) routers parse, process, and modify IP headers
 (b) routers perform the same function as switches but the two are marketed in very different ways
 (c) switches hold IP routing tables only for only local subnets
 (d) switches connect only to hosts, whereas routers connect networks  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.2 of the course notes.  
 . 
 Which of the following is the most credible threat to the continuing success of the Internet Protocol (IP) as currently deployed?  
 

  (a) Widespread deployment of fiber optics will call for more than 8192 fragments per datagram.
 (b) The IP address space will be exhausted.
 (c) Big multimedia files will no longer fit into IP datagrams.
 (d) Router memory will become insufficient to keep track of an exponentially increasing number of circuits.  

 Correct answer is  (b)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.3 of the course notes.  
 

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 2. 
 The network interface card of a Web server that you manage has developed sporadic problems. You measure the packet loss rate from your desktop computer and immediately decide to replace the network card. After this simple operation, the Web server successfully rejoins the network, as confirmed by your officemate using her desktop computer. You eagerly go to your desktop to measure the improvement, but find instead that the Web server is not responding to any of your packets. What is your diagnosis?  
 

  (a) Your desktop computer is still trying to contact the server's old network card.
 (b) Your desktop computer's network card does not work.
 (c) The new network card does not work.
 (d) The Domain Name System (DNS) has not yet updated its entry for the Web server.  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.5 of the course notes.  
 

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 3. 
 The class B IP network 128.2.x.x has been assigned to Carnegie Mellon University. To relieve congestion in its internal LAN, Carnegie Mellon has decided to subnet this IP network. This will have which of the following consequences? 
The configuration of the subnets will have to be announced to routers all over the world by notifying NIC and/or IANA. 
A computer may need to change its IP address when moved from one office to another. 
Some bridges, hubs, or switches will need to be replaced with routers. 
 
 

  (a) I and III only
 (b) III only
 (c) II and III only
 (d) I, II, and III  

 Correct answer is  (c)  

 Your score on this question is: 0.00  

 Feedback: 
   See section 1.3.3 of the course notes.  
 

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 4. 
 You have just connected a newly purchased computer to your LAN. Eagerly, you boot it for the first time and find with great disappointment that the machine will not be able to use the network because of an IP address conflict. How did the computer find the conflict?  
 

  (a) It sent a packet to 127.0.0.0 and did not receive any replies.
 (b) It sent an IP packet to its own IP address and did not receive any IP packets within a timeout period.
 (c) It sent an Ethernet frame to its own Ethernet address, and some other machine responded.
 (d) It sent an ARP packet to the local broadcast address and received a reply.  

 Correct answer is  (d)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.5 of the course notes.  
 

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 5. 
 A network uses a routing algorithm that uses paths with the least number of hops. These paths are computed periodically using a shortest-path algorithm. In this network, datagrams 
are routed around congested links 
may traverse the same router twice 
will always reach their destination 
 
 

  (a) none
 (b) III only
 (c) I and II only
 (d) I and III only  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.2 of the course notes.  
 

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 6. 
 A router is installed to interconnect 4 subnetworks with MTUs of 1024, 2048, 576, and 1556 bytes respectively. Nodes A and B are connected to the first and second subnets, respectively. An application on node A sends a 4096-byte datagram (e.g., using UDP) to an application on node B. How many IP fragments will the router process as a result?  
 

  (a) 2
 (b) 5
 (c) 1
 (d) 4  

 Correct answer is  (b)  

 Your score on this question is: 0.00  

 Feedback: 
   See section 1.3.4 of the course notes.  
 

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 7. 
 The following Java declaration 
InetAddress addr = InetAddress.getbyName("www.example.com");

will fail when  
 

  (a) all known DNS servers are down
 (b) www.example.com does not respond to ARP requests
 (c) a route to www.example.com is not available
 (d) www.example.com is down  

 Correct answer is  (a)  

 Your score on this question is: 10.00  

 Feedback: 
   See Chapter 10 of the yellow book. See section 1.3.5 of the course notes.  
 

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 8. 
 At which of the following layers of the OSI protocol stack can the Internet Control Message Protocol be implemented? 
Network 
Transport 
Data link 
 
 

  (a) I or II only
 (b) II only
 (c) III only
 (d) I only  

 Correct answer is  (d)  

 Your score on this question is: 0.00  

 Feedback: 
   See section 1.3.6 of the course notes.
   (a) A transport-layer protocol would be oblivious to network layer failures.  
 

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 9. 
 A router is installed to interconnect 4 subnetworks with MTUs of 1024, 2048, 576, and 1556 bytes respectively. Nodes A and B are connected to the first and second subnets respectively. An application on node A sends a 4096 byte datagram (e.g. using UDP) to an application on node B. How many incoming IP headers will the router process that have the MF (more fragments) flag set?  
 

  (a) 0
 (b) 1
 (c) 5
 (d) 4  

 Correct answer is  (d)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.4 of the course notes.  
 

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 10. 
 A difference between routers and switches is that  
 

  (a) switches connect only to hosts, whereas routers connect networks
 (b) switches hold IP routing tables only for only local subnets
 (c) routers perform the same function as switches but the two are marketed in very different ways
 (d) routers parse, process, and modify IP headers  

 Correct answer is  (d)  

 Your score on this question is: 10.00  

 Feedback: 
   See section 1.3.2 of the course notes.  
 


 9. 
 In a network that uses shortest-path-per-hop routing, router A receives a datagram destined for host H and determines that the shortest path to H traverses routers B, C, and D, in that order. The datagram may traverse 
B and D, but not C 
B, C, and D, in that order 
C and D, but not B