Module 12: Network Programming Design

Question 1

denial of service attacks

Answer 1

bad attackers try to overwhelm a web server by making requests at the same time, using up all the resources on the web server; makes it difficult to distinguish between fake and legitimate traffic

Question 2

event-driven programming

Answer 2

rather than using blocking system calls, event-driven programming allows higher performance and resource utilization by allowing functionality to continue or sleeping until the desired event occurs

• -event loop
• -event handlers

Question 3

network stack: OSI model

Answer 3

a formal, standard representation of networking that splits the network functionality into seven layers

Question 4

network stack: internet model

Answer 4

an informal representation of networking that splits the network functionality into five layers; this model groups the application, presentation, and session layers of the OSI model together

1. physical layer: wires etc between physical systems
2. data link layer: determines how the raw bytes should be transferred over the physical links. the link layer puts the raw bytes into messages, performs error detection and correction in transferred data, includes functions for reliable delivery, and determines where and when to send the data over links
3. network layer: includes IP and message routing within the network
4. transport layer: TCP and UDP; creates network communication channels between different processes on the same or on different machines through the use of sockets
5. application layer: includes the user level processes that require network communication

Question 5

interface

Answer 5

accepted form of representing and accessing data such that the user can decode the information

Question 6

protocol

Answer 6

rules and formats that govern the communication over network boxes

Question 7

data link layer

Answer 7

data frame: grouping of raw data bits; the recipient can identify the frames by the particular sequences of bits that represent the start and end

MAC address: unique address that identifies your network card; 48 bit address space

Question 8

network layer

Answer 8

packet - a method of wrapping data with its control information
router - a networking device that is connected to multiple network links and determines where to send a packet based
switch - switches forward messages between devices

Question 9

encapsulation

Answer 9

each layer can only see the service provided by the layer immediately below it