【Computer Network Fundamentals】Test 1 Overview

True or False

1. The public network is generally a wide area network, and the private network must be a local area network. x

2. Entities using the services of this layer can only see the services but not the underlying protocols that provide the services. √

3. A protocol is a collection of rules governing communication between two peer entities (or entities). √

4. The Internet originated in the United States, so the Internet is governed by the United States. x

5. Protocols are "vertical" and services are "horizontal". x

multiple choice

1. In computer network architecture, the data unit exchanged by adjacent layers is called ( A ).
   A. SDU
   B. IDU
   C. PDU
   D. ICI

2. Which of the following words can represent the Internet or the Internet? ( B )
   A. internet
   B. Internet
   C. www
   D. network

3. In the OSI reference model, the layer that can realize routing, congestion control and interconnection functions is ( D ).
   A. Transport layer
   B. Application layer
   C. Physical layer
   D. Network layer

4. Non-performance indicators of computer networks do not include ( D ).
   A. Cost
   B. Quality
   C. Reliability
   D. ISP distance

5. The development of Internet standards needs to go through three stages, the following is not part of ( D ).
   A. Internet-Draft
   B. Proposed Standard
   C. Internet Standard
   D. Standard Protocol

6. In the following data exchange methods, the transmission delay of data through the network is long and the length is not fixed, and it is ( B ) that cannot be used for voice data transmission.
   A. Circuit switching
   B. Message switching
   C. Datagram packet switching
   D. Virtual circuit packet switching

7. The communication modes between the end systems at the edge of the network can usually be divided into two categories, namely client-server mode and ( C ) mode.
   A. PPP
   B. c/s
   C. Peer
   D. Datagram

8. Computer network is the product of the development of computer technology and ( A ) technology.
   A. communication
   B. wireless
   C. transmission
   D. telecommunications

9. The packet switching method is to divide a long message into several shorter packets with a fixed maximum length. Different from the message exchange method, the packet exchange method has ( C ).
   A. Message header
   B. Message trailer
   C. Packet number
   D. Routing

10. A collection of rules, standards or conventions established for data exchange in a computer network is called ( C ).
    A. Protocol cluster
    B. Architecture
    C. Network protocol
    D. Network protocol

11. The largest computer network in the world is ( A ).
    A. Internet
    B. Internet
    C. Alibaba Cloud
    D. NFS network

12. The resources shared by the computer network are ( D ).
    A. Router, switch
    B. Domain name, network address and MAC address
    C. Computer files and data
    D. Computer software, hardware and data

13. The error in the following description about network topology is ( A ).
    A. Network topology studies the relationship between nodes in resource subnets
    B. Topology abstracts entities into points that have nothing to do with their size and shape
    C. Basic network topologies include star, ring, bus, tree and network Type
    D. Network topology has a significant impact on network performance, system reliability, and communication costs

14. Which of the following descriptions of network architecture concepts is wrong ( D ).
    A. The network architecture is a collection of network hierarchical structure models and protocols of each layer
    B. The network architecture is abstract, while the technology to realize the network protocol is specific
    C. The network architecture defines the functions that the computer network should realize
    D . All computer networks must follow the OSI architecture

15. Which of the following descriptions about the structural characteristics of Internet core switching and edge parts is wrong ( C ).
    A. The Internet system can be regarded as composed of two parts, the edge part and the core switching part.
    B. The core switching part includes a wide area network, a metropolitan area network and a local area network interconnected by a large number of routers.
    C. The end system of the edge part is composed of routers.
    D. Network The application program runs on the end system, and the core exchange part provides services for the application process communication

16. The network layer protocol in the TCP/IP system provides ( A ).
    A. Connectionless unreliable packet service
    B. Connectionless reliable packet service
    C. Connection-oriented reliable virtual circuit service
    D. Connection-unreliable virtual circuit service

17. The computer network can be divided into the edge part and the core part in terms of working methods, and the core part is usually called ( B ).
    A. Resource subnet
    B. Communication subnet
    C. Intranet
    D. Router

18. The order of the OSI reference model from bottom to top is ( B ).
    A. Application layer, presentation layer, session layer, transport layer, network layer, data link layer, physical layer B. Physical
    layer, data link layer, network layer, transport layer, session layer, presentation layer, application layer
    C. Physical layer, data link layer, transport layer, network layer, session layer, presentation layer, application layer
    D. application layer, presentation layer, session layer, network layer, transport layer, data link layer, physical layer

19. Widely used topology in wide area network is ( D ).
    A. star
    B. ring
    C. tree
    D. mesh

20. The error in the following description of the basic concepts of the OSI reference model is ( A ).
    A. The "open" in the term "OSI reference model" refers to an operating system that can be used on any kind of computer
    B. The OSI reference model defines the hierarchical structure of an open system and the interrelationships between layers
    C. The OSI reference model is not A standard, but a conceptual framework used in the formulation of the standard
    D. The service definition of OSI specifies the services provided by each layer in detail, and does not involve the specific implementation method of the interface

Analytical questions

1. Place the correct alphabetic number in front of each of the following OSI layer names so that each name matches the description you think is most appropriate.

application layer b
transport layer g
network layer d
data link layer a
physical layer e

a. specifies techniques for moving data between adjacent nodes along network links on a network
b. organizes and structures interactions between communicating application processes
c. provides distributed processing and access
d. is used in many open systems Constructed environment to allow communication between network entities
e. Connecting systems to physical communication media
f. Coordinating data and data format conversions to meet the needs of application processes
g. Transferring data between end point systems with errors Recovery and flow control functions

2. Pick 10 from the 20 definitions given, and fill in the blank space before the corresponding term with the letter identifying the definition.

1. Grammar C
2. Network Architecture G
3. RFC Q
4. OSI Reference Model H
5. Network Protocol A
6. Transport Layer L
7. Semantics B
8. Hierarchical Structure E
9. OSI Environment N
10. Network Interface Layer O

A. Communication rules, conventions, and standards for network data exchange.
B. Explain the meaning of each part of the control information.
C. Describe the structure and format of user data and control information.
D. A detailed description of the order in which events are implemented.
E. The most basic way to deal with computer network problems.
F. A connection point at which information is exchanged between adjacent layers within a networked host.
G. A collection of network hierarchy models and protocols at each layer.
H. The ISO/IEC 7498 standard defines a seven-layer structure model for network interconnection.
I. The lowest layer of the OSI reference model.
J. The data transfer unit of the data link layer.
K. The data transmission unit of the network layer.
L. Layers that enable reliable end-to-end connectivity and data transfer services.
M. A level that implements communication process control between applications.
N. Including the 7 layers from the application layer to the physical layer in the host and the structure of the communication subnet.
O. The layer in the TCP/IP reference model that corresponds to the data link layer and the physical layer of the OSI reference model.
P. An unreliable, connectionless transport layer protocol.
Q. A type of document that publishes technical research progress and standards among network technicians.
R. The most authoritative international organization for Internet global coordination and cooperation.
S. An organization dedicated to the research of Internet protocols, architecture, applications, and related technologies.
T. The organization responsible for Internet domain name registration and domain name database management.

Application questions

1. $$Assume\; that\; the\; propagation\; speed\; of\; the\; signal\; on\; the\; medium\; is\; about2\ast 10^{8}m/s,\; the\; data\; transmission\; rate\; is10Mbps,\; when\; the\; media\; lengthLis500mand3km,\; please\; calculate\; the\; number\; of\; bits\; being\; transmitted\; in\; the\; media\; respectively.$$

(1) When L is 500m, the number of bits is 25 .

(1) When L is 3km, the number of bits is 150 .

2. $$Length\; of\; transmission\; medium\; between\; hostsD=1000km,\; the\; propagation\; speed\; of\; the\; signal\; on\; the\; medium\; is\; about2\ast 10^{8}m/s,\; please\; calculate\; separately:$$

(1) When the data length is 1000bit and the data sending rate is 100Kbps, the sending delay is 10 milliseconds, and the propagation delay is 5 milliseconds.

(2) When the data length is 108bit and the data sending rate is 1Gbps, the sending delay is 100 milliseconds, and the propagation delay is 5 milliseconds.

3. $$There\; is\; a\; point-to-point\; link\; with\; a\; length\; of80km.If\; the\; propagation\; rate\; of\; data\; on\; this\; link\; is2\ast 108m/s,\; what\; is\; the\; bandwidth\; of\; the\; link\; so\; that\; the\; propagation\; delay\; is\; as\; large\; as\; the\; sending\; delay\; of\; sending\; a400-byte\; packet?$$
   The calculated link bandwidth is8Mbps