Chapter 4: Networking and The Internet

Question 1

Types of network scopes

Answer 1

• PAN (Personal area network) example: wireless headset, mouse
  
  • LAN (Local area network) one location
  • MAN (Metropolitan network)
  • WAN (Wide area network) several locations; possibly world wide

Question 2

Types of network topologies

Answer 2

• Bus: all machines are connected to a common communication line (a bus) example: Ethernet
• Star: all other machines are connected to one central machine, called the access point (example: WIFI)

Question 3

Types of network devices

Answer 3

• Hub: connects machines into a network (bus topology)
• Access point: connects machines into a network (star topology)
• Switch (a smart hub): connects several machines or buses into a network; only sends necessary traffic between the buses or machines.
• Router: connects several networks into an internet (network of networks)
  Each router maintains a forwarding table describing where messages should be sent depending on their destination addresses.

Question 4

Inter-process communication

Answer 4

• Client/server: client request server services, and server serve clients requests
• Peer-to-peer (P2P): the peers provide service to and retrieve service from each other

Question 5

Distributed systems

Answer 5

• Distributed systems: consists of software units that execute on several different computers
• Cloud computing: huge pools of shared computers can be allocated for use by clients as needed.

Question 6

Internet architecture

Answer 6

• ISPs: Internet Service Provider (maintains the internet)
• End systems / hosts: devices that individual user connect to internet via som ISP
• Hot spot: areas where wireless internet access is provided

Question 7

Internet addressing

Answer 7

• IP address: Unique identifying address to a computer on Internet
• ICANN - gives IP addresses to ISPs
• IPv4: addresses are 32 bits = 2^32 - Network layer
• IPv6: addresses are 128 bits = 2^128, usually written in 8 groups of 4 hexadecimal digits

Question 8

Internet domains

• Domains:
• Top level domains:
• Domain name system (DNS):
• DNS server (name server):
• DNS lookup:

Answer 8

• Domains: Internet addressing by mnemonic names for example: www.google.com overseen by ICANN
• Top level domains: country codes and com, gov, ord, net, etc
• Domain name system (DNS): converts domain names to IP addresses
• DNS server (name server): provides address translations
• DNS lookup: the process of using DNS to perform a translation

Question 9

Internet Applications

Answer 9

• File transfer using FTP (File Transfer Protocol) - Application layer
• Remote computer access using SSH (Secure Shell Protocol)
• World Wide Wem using HTTP (Hypertext transfer protocol)
• Email using SMTP (Simple mail transfer protocol) and MIME (multipurpose internet mail extensions) - Application layer
• VoIP: voice over IP
• Multimedia streaming: real time audio and video

Question 10

World Wide Web

Answer 10

• Hyper text: documents linked by hyperlinks
• HTML (hypertext markup language) - to create documents
• Browser (web client) - present documents to a user
• Web Server: provides access to documents
• URL or nowadays URI: identifies a document
• HTTP: protocol for transferring documents

Question 11

Internet software layers

Answer 11

• Application: constructs messages with addresses
• Transport: chops messages into packets
• Network: handles routing through internet
• Link: handles actual transmission of packet

Question 12

TCP/IP protocol suite

Answer 12

• Transport layer:
  Transmission control protocol (TCP) Reliable (If a piece is missing it will ask to resend)
  User datagram protocol (UDP) efficient

Question 13

• Network layer:

Answer 13

IPv4

IPv6

Question 14

Security

• Attacks:
• Protection:

Answer 14

• Attacks:
  Malware (viruses, worms, trojan horse, spyware, phishing software)
  Denial of service (DoS)
  Spam

- Protection:
Antivirus software
Firewalls
Spam filters
proxy servers

Question 15

Encryption:

• HTTPS -
• Public key encryption:
• Certificate:

Certificate authorities:

Answer 15

• HTTPS - Secure version of HTTP using SSL (Secure Sockets Layer)
• Public key encryption:
  encrypt by public key and decrypt by private key or
  encrypt by private key (digital signature) and decrypt by public key
• Certificate: package of name (identity) and public key
  Certificate authorities: guarantee certificates authenticity