First, the choice (20%)
1. (2009 Zhenti 408) in the OSI reference model, the first bottom-to-end service level is ()
A, the data link layer
B, the transport layer
C, session layer
D, the application layer
Answer: B, end to end concept study and mastery of the OSI reference model.
2. (Original) when implementing a TCP-based web application server process flow is correct ()
A、socket() -> bind() -> listen() -> read()/write() -> close()
B、socket() -> bind() -> listen() -> accept() -> read()/write() -> close()
C、socket() -> connect() -> read()/write() -> close()
D、socket() -> bind() -> listen() -> connect() -> read()/write() -> close()
Answer: B, this title examines the basic concepts of the socket.
3. (Original) if Manchester encoding, the transmission rate of 100Mbps modulation rate is required ()
A. 200MBaud B. 400MBaud C. 50MBaud D. 100MBaud
Answer: A, study the basic concepts.
4. In the TCP / IP architecture, ICMP protocol is to offer services directly ()
A． PPP B． IP C． UDP D． TCP
A: B, ICMP network layer protocol, ICMP packets encapsulated as a data field in an IP packet.
5. (The computer 408 Exams) following a network device, it is possible to suppress the broadcast storm is ______.
Repeaters Hubs Ⅰ Ⅱ Ⅲ Ⅳ bridge router
A. Only Ⅰ and Ⅱ B. Only Ⅲ
C. Only Ⅲ and Ⅳ D. Only Ⅳ,
A: D; physical layer repeater devices and hubs are neither isolated nor broadcast domain collision domain; bridge collision domains may be isolated, but without isolation broadcast domains; router in the network layer both collision domain isolation, but also a broadcast domain; VLAN or virtual local area network can also be separate broadcast domain. For non-isolated broadcast domains equipment, interconnection of different networks they belong to the same broadcast domain, thus expanding the scope of broadcast domains, more prone to network storm.
6 . (408 Exams computer) network layer to the query path through what?
A, the routing table B, ARP table C, MAC address table D, the bridge table
Answers: A
Analysis: study router works. Routers at the network layer is an extremely important device, each by a router forwarding. Check the router packet arriving at the value of a field in the header, and then use that value to query the forwarding in the router to determine how to forward the packet. Is the result of the query will be forwarded packet router link interface. You can view the routing table with netstat -r or route
7. (cattle off network) Which of the following statement is correct ()
A, hub may amplify the received signal
B, the hub having filtering.
C, the hub having a detection path
D, the hub having a switching function
Answers: A
Analysis: study the working principle of the HUB. HUB and the retransmission functions as signal amplification effect only in the network, an object is to expand the transmission range of the network, without the ability to have the directional transmission signal.
8. The following description of the switch on the right is (A)
A．PPP
B．ARP
C．UDP
D．SMTP
Parsing: D . Study application services and protocols used. ARP protocol will be used when the computer does not know the MAC address of a host MAC address corresponding to the query IP address, B may be used;; when the access network may use the PPP protocol, A and may be used when accessing the Web site, if the DNS IP address of the corresponding domain name is no buffer memory, to use the DNS query protocol with the corresponding IP address of the domain name, DNS is a UDP-based protocol, it is possible to use C, SMTP mail client to use only send e-mail, or mail server will be used when sending messages to other mail servers, simply access the Web page can not be used.
Second, the essay questions (10% each, a total of 30%)
1. (computer network supporting materials) Description of the TCP three-way handshake
First of all server-side calls socket () to create a server-side socket calls after bind () bind to create a socket is the socket file descriptor get, after calling acppet () blocking yourself waiting for client connections.
The client calls the same socket () to create a socket client, after the call connect () to connect to the server according to the locking socket server [server], in this case a TCP segment SYN = 1, seq x is a random number .
After the server accept () blocking section receives the packet is interrupted, and sends a TCP segment, SYN = 1, ACK = 1, seq random number y, ack = x + 1.
Poststate client receives the message segment ESTABLISED, ACK = 1, seq = x + 1, ack = y + 1.
The server receives post their status as they ESTABLISED. At this three-way handshake is over.
2. (Baidu library) What is DNS? What are the main functions? How to understand the domain name www.edu.cn?
The answer: DNS is Domain Name Service that Domain Name Service, which provides two-way analytic functions between domain names and IP addresses that can resolve a domain name into the corresponding IP, the reverse may be resolved to the corresponding IP domain name.
www.edu.cn top-level domain is cn, on behalf of China, and is the second-level domain edu, on behalf of educational institutions, www is the host name.
3. The connection-oriented service advantages and disadvantages?
A: Advantages: easy programming; automatic handling packet loss, packet reordering; automatic validation data error, the connection state processing.
Cons: There is a separate socket for each connection, consume more resources; does not send any packets on an idle connection; server is always running because of the customer's collapse, leading to excessive and useless socket depletion of resources.
Third, the comprehensive title (50%, 25% each)
1. Assuming two autonomous systems Internet network configuration as shown, autonomous system AS1 two subnets connected by routers R1 configuration; autonomous system AS2 by the router R2, R3 and interconnecting the three sub connector configuration. Each subnet address, the interface portion of the address of the interface name R2, Rl and R3 are as shown in FIG.
please answer the following question.
(1) assuming the routing table structure in the table below. Please polymerization techniques using the routing, routing table given R2, requirements include routes to all subnets in the drawings, and the routing entry in the routing table as small as possible. 
Analysis: In AS1 in 153.14.5.0/25 subnet and subnet 153.14.5.128/25 polymerization may subnet 153.14.5.0/24;
In AS2, subnet and subnet 194.17.21.0/24 can 194.17.20.0/25 polymerization subnet 194.17.20.0/23, but lacks 194.17.20.128/25; 194.17.20.128/25 subnet R2 individually connected to interface E0.
R2 can then be obtained routing table is as follows:
Test: route aggregation and routing table structure.
(2) if R2 receives an IP packet destination address is 194.17.20.200, R2 of the packet will be forwarded via which interface?
Analysis: The IP address in the routing table and 194.17.20.128/25 194.17.20.0/23 two routing table entries are matched according to the longest match principle, R2 forwarding the IP packet through the E0 interface.
Test: CIDR longest prefix match.
Which routing protocol utilizing between (3) R1 and R2 exchange routing information? The packet routing protocol which is encapsulated into protocol packets for transmission?
Analysis: using BGP4 (or BGP) between R1 and R2 exchange routing information;
the packet is encapsulated into the BGP4 protocol TCP segment for transmission.
Test: Exterior Gateway Protocol - Border Gateway Protocol BGP4.
2. As shown in FIG topology of a network under the title, wherein R is a router, the IP address of the host H1 ~ H4 configurations and IP addresses for R configuration as shown. There are several existing Ethernet switch (no VLAN function) and routers to choose two types of internetworking devices.
please answer the following question:
(1) Device 1, Device 2 and 3, respectively equipment should choose what type of network equipment?
(2) the device 1, the device 2 and device 3, which interfaces need several devices to configure the IP address? And configure the correct IP address for the corresponding interface.
(3) To ensure that the host H1 ~ H4 able to access the Internet, R need to provide any services?
(4) If the host transmits a H3 destination address 192.168.1.127 for IP packets, the network in which several host receives the data packets?
answer:
(1) Equipment 1: router apparatus 2: Ethernet switch device 3: Ethernet switch
(2) device I interface requires IP address configuration; IFI device 1, the interface IF2 is IF3 and
IP address are: 192.168. 1.254.192.168.1.1 and 192. 168.1.65.
(3) R NAT required to provide services
(4) H4 host receives the datagram.