1. The host or end system accesses the Internet through ( ).
- A. ISP
- b. Modem
- C. switch
- D. router
P21: End systems (PCs, smartphones, web servers, email servers, etc.) are connected to the Internet through an access ISP.
2. Hosts are generally divided into two categories: clients and ( ) .
- A. End system
- B. mainframe
- c. Data center
- D. server
3. Access network refers to the physical link connecting the end system to ( ) .
- A. Router
- b. Internet
- C. Edge routers
- D. server
4. The following ( ) are network access methods commonly used in family residences.
- A. ADSL
- b. Ethernet
- C. Wi-Fi
- D. 3G
ADSL: Asymmetric Digital Subscriber Line
5. There are two models of computer network architecture, ISO/OSI and TCP/IP. The following layers only exist in the ISO/OSI model ( ).
- A. Network layer
- B. Session layer
- C. Application layer
- D. Transport layer
DJ1-5 reference model, network attack
The ISO/OSI model has a presentation layer and a session layer.
6. Assume that there is only one packet switch between the sending host and the receiving host. The transmission rates between the sending host and the switch and between the switch and the receiving host are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, the total end-to-end delay for sending a packet of length L is ( ). (ignoring queuing delay, propagation delay and processing delay)
- A. 2L / R1
- B. 2L / R2
- C. L / (R1 + R2)
- D. L / R1 + L / R2
This problem only makes us consider the transmission delay.
7. Which of the following delays is affected by network congestion.
- A. Processing Latency
- B. Transmission delay
- C. Queuing delay
- D. Propagation delay
The other three delays are fixed, only the queuing delay depends on how many packets are queued in the router output buffer.
8. A packet with a length of 1000 bytes passes through a 2Mbps Ethernet link with a distance of 2900km, where the propagation rate is 2.9 * 10^8 m/s, and what is the propagation delay?
- A. 10 ms
- B. 0.1 s
- C. 1 ms
- D. 1 s
What is useless in the title is the noise.
9. Host A sends a 6MB file to host B. There are 3 links on the path from host A to host B, and the rates are 1Mbps, 800kbps, and 2Mbps. The file is transmitted from host A to host B in about how long it takes?
- A. 24 s
- B. 48 s
- C. 7.5 s
- D. 60 s
The transmission delay mainly depends on the bottleneck link. 800kbps is the bottleneck link in the 3-segment link, so the transmission delay mainly depends on it: 6MB / 800kbps = 60 s, pay attention to the unit!
10. Which five layers of protocols does the Internet protocol stack contain?
- A. Application layer, transport layer, network layer, link layer, physical layer
- B. Application layer, presentation layer, transport layer, link layer, network layer
- C. Application layer, presentation layer, network layer, link layer, physical layer
- D. Application layer, transport layer, session layer, network layer, physical layer
11. In the network protocol stack, which layer is responsible for sending and receiving data packets between end-to-end?
- A. Network layer
- B. Data Link Layer
- C. Transport layer
- D. Application layer
12. Which layer of protocol do SMTP, FTP, TCP, and IP belong to?
- A. Application layer, transport layer, network layer, network layer
- B. Transport layer, application layer, transport layer, network layer
- C. Application layer, transport layer, transport layer, network layer
- D. Application layer, application layer, transport layer, network layer
13. In the layered protocol, what is the direction of data transmission between the sender and the receiver?
- A. Sender from bottom to top, receiver from bottom to top
- B. Sender from bottom to top, receiver from top to bottom
- C. Sender from top to bottom, receiver from top to bottom
- D. Sender from top to bottom, receiver from bottom to top
14. Which of the following statements is correct ( ).
- A. Circuit switching network is divided into virtual circuit network and datagram network
- B. TCP is connection-oriented, UDP is connection-oriented
- C. Packet switching network is divided into time division multiplexing and frequency division multiplexing
- D. The virtual circuit network must be connection-oriented
Packet switching network is divided into virtual circuit network and datagram network, and circuit switching network is divided into two types: time division multiplexing and frequency division multiplexing.
15. The path selection function is completed on ( ) of the OSI model.
- A. Physical layer
- B. Transport layer
- C. Network layer
- D. Data link layer