Networking and the Internet - Chapter 4
1. What is the difference between a switch and a router?
A switch connects multiple "buses" (and/or computers) to a network. A router connects multiple different networks to a network of networks (the internet).
____________________________________________________
2. What are the two models for inter-process communication?
Client/server and peer-to-peer.
____________________________________________________
3. What is an IP address?
A unique numerical address for a computer connected to the Internet.
____________________________________________________
4. What is DNS?
Domain Name System translates domain names to IP addresses.
____________________________________________________
5. What do bus and star mean in terms of network topology?
Bus topology means that all devices are connected to a common communication line, called a bus. Star topology means that all other devices are connected to a central device, called an access point.
____________________________________________________
6. What does cloud computing mean?
Large pools of shared computers that can be allocated for use based on demand.
____________________________________________________
7. What is the protocol used by the World Wide Web application?
HTTP (Hypertext Transfer Protocol).
____________________________________________________
8. Which Internet software layer does the UDP (User Datagram Protocol) belong to?
Transport layer.
____________________________________________________
9. What is the main difference between IPv4 (IP Version 4) and IPv6 (IP Version 6)?
IPv4 addresses are 32 bits and IPv6 addresses are 128 bits, which means there are many more IPv6 addresses than IPv4 addresses.
____________________________________________________
10. Which Internet software layer does the FTP (File Transfer Protocol) belong to?
Application layer.
____________________________________________________
11. What is a certificate in connection with public key encryption?
A package consisting of name/identity and public key, which certifies that one is who they claim to be.
____________________________________________________
12. Give an example of a type of malware?
Viruses, worms, Trojan horses, spyware, phishing software (it’s enough to mention one).
____________________________________________________
13. What is a LAN?
Local Area Network.
____________________________________________________
14. Which Internet software layer does the TCP (Transmission Control Protocol) belong to?
Transport layer.
____________________________________________________
15. What is a distributed system?
Consists of software units that execute on several different computers.
____________________________________________________
16. What is the organization responsible for assigning IP numbers (it’s enough to mention the abbreviation)?
ICANN (Internet Corporation for Assigned Names and Numbers).
____________________________________________________
17. What does DNS lookup mean?
The use of DNS (Domain Name System) to translate from a domain name to an IP address.
____________________________________________________
18. What does a (network) hub do?
Connects computers to a network.
____________________________________________________
19. To which Internet software layer does the SMTP (Simple Mail Transfer Protocol) belong?
Application layer.
____________________________________________________
20. What does a web server do?
Provides access to various web resources, such as web pages.
____________________________________________________
21. What is the purpose of a URL/URI?
To uniquely identify a web resource, e.g., a web page.
____________________________________________________
22. What are the two common Internet protocols for the transport layer?
TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
____________________________________________________
23. To which Internet software layer does the IPv6 protocol belong?
Network layer.
____________________________________________________
24. What is the encryption technique widely used on the Internet that allows parties not to need access to a common key in advance?
Public key encryption (e.g., RSA algorithm).
____________________________________________________
25. What are Internet domains, and what is their purpose?
Mnemonic names for numerical IP addresses, which are easier for people to remember and mean that one can change IP addresses but still keep the same mnemonic address.
____________________________________________________
26. Give two examples of Internet applications with open (publicly available) protocols?
For example, HTTP (Hypertext Transfer Protocol) and FTP (File Transfer Protocol).
____________________________________________________
27. What is the difference between the protocols HTTP and HTTPS?
Traffic over HTTP is not encrypted, while traffic over HTTPS is encrypted (public key encryption).
____________________________________________________
28. Briefly explain the difference between the network components hub, switch, and router?
* A hub connects machines/network devices to a network and sends all traffic to all connected devices.
* A switch is a type of smarter hub that connects network devices in the same way as a hub but only sends traffic between the devices/ports that need to communicate.
* A router connects multiple networks to each other and forwards traffic between networks.
____________________________________________________
29. What is transferred by the various protocols FTP, HTTP, SMTP?
- FTP transfers files.
- HTTP transfers various types of resources for, e.g., web pages (e.g., HTML documents, images, audio, etc.).
- SMTP transfers electronic mail.
____________________________________________________
30. What is a certificate? Can you trust all certificates equally? Justify!
A certificate is an electronic document that shows who owns a specific identity or encryption key. How much one trusts a certificate depends on the trust in the issuer of the certificate. Some certificate authorities, e.g., certain government entities, enjoy a higher level of trust, while a certificate issued by oneself or a less credible or serious actor is worth less trust. Compare with common identity documents – a passport issued by the state through the Police Authority is worth significantly more than a passport made at home.
____________________________________________________
31. What is it called when a web client queries a specific type of server to translate a domain name to an IP number?
DNS lookup.
____________________________________________________
32. Which Internet protocol for the transport layer is most reliable?
TCP (Transmission Control Protocol).
____________________________________________________
33. What does a digital signature mean in public key encryption, i.e., that when transferring a file, one can guarantee the sender's identity?
That the file is encrypted with the sender's private key.
____________________________________________________
34. What characterizes a distributed system?
Consists of software units that execute on several different computers.
____________________________________________________
35. How many times more addresses can be represented with IPv6 compared to IPv4 (as usual, you don’t need to calculate a value, just present a correct calculation)?
2^128 / 2^32 = 2^96
____________________________________________________
36. What are the four Internet software layers?
Application, transport, network, link.
____________________________________________________
37. What is HTML used for?
HTML (Hypertext Markup Language) is a language used to create/describes web pages.
____________________________________________________
38. What is the language used to describe web pages called?
HTML (Hypertext Markup Language).
____________________________________________________
39. In public key encryption, the concept of certificate is used; what is it?
A package consisting of name/identity and public key, which, if issued by a certificate authority, certifies that one is who they claim to be.
____________________________________________________
40. In public key encryption, the concept of certificate authority is used; what is it?
An organization that issues certificates (a package consisting of name/identity and public key), which certifies that one is who they claim to be.
____________________________________________________
41. What is an advantage of using TCP instead of UDP? What is a disadvantage?
An advantage is that it is more reliable; a disadvantage is that it is slower.
____________________________________________________
42. What is an advantage of using UDP instead of TCP? What is a disadvantage?
An advantage is that it is faster; a disadvantage is that it is less reliable.
____________________________________________________
43. Briefly explain the concept of client-server!
A model where clients request services to be performed by servers that provide the services.
____________________________________________________
44. What is SMTP used for?
SMTP is a protocol for handling electronic mail.
____________________________________________________
45. If person A wants to send a message to person B, encrypted according to public key encryption, so that no one else but B can read the message. What does the message need to be encrypted with before the message is sent from A?
Person B's public key.
____________________________________________________
46. If person A wants to send a message to person B, encrypted according to public key encryption, so that no one else but A can have sent the message. What does the message need to be encrypted with before the message is sent from A?
Person A's private key.
____________________________________________________
47. To protect a computer or a network of computers, a system consisting of software and possibly hardware is often used to inspect, block, and filter incoming and outgoing network traffic. What is such a system called?
Firewall.
____________________________________________________
48. To better protect a network of computers, an intermediary computer is often used, which means that communication does not go directly between a client on the network and an external server. What is such a computer called?
Proxy server.
____________________________________________________
49. What is a hub and a router used for?
A hub connects machines/network devices to a network. A router connects multiple networks to the internet (network of networks).