BM6

Question 1

What is the core mechanism of Packet Switching?

Answer 1

Messages are split into packets that travel along independent network paths, with routers using the destination IP address to determine the next link.

Question 2

What is the function of the Network (IP) Layer in the TCP/IP stack?

Answer 2

It moves IP packets (datagrams) between hosts and routers across the internet, adding or removing source and destination IP addresses.

Question 3

What is the primary role of the Transport Layer (TCP)?

Answer 3

It establishes a reliable, two-way channel (pipe) between applications on two hosts, guaranteeing message delivery and correct reassembly order.

Question 4

What is a TCP/IP Socket?

Answer 4

It is one endpoint of a two-way communication link between two network programs, uniquely identified by a combination of an IP address and a port number.

Question 5

What is the TCP 3-way Handshake used for?

Answer 5

It is a sequence of messages (SYN, ACK) used by the TCP protocol to reliably establish a connection between the client and server.

Question 6

What are Well-Known Ports (System Ports)?

Answer 6

Port numbers in the range 0-1023 assigned permanently by IANA to standard services (e.g., HTTP uses 80, SMTP uses 25).

Question 7

What are Client Ports (Dynamic/Ephemeral Ports)?

Answer 7

Temporary port numbers (49152-65535) allocated by the TCP layer to identify the client application process during a connection.

Question 8

What is the role of the Application Layer?

Answer 8

It provides the interface for running programs (processes) to exchange messages using specific application-layer protocols (e.g., HTTP, FTP).

Question 9

Which protocol is used for sending email?

Answer 9

SMTP (Simple Mail Transfer Protocol), which transfers the message text from the client to a mail server listening on port 25.

Question 10

Which protocol is used for retrieving email?

Answer 10

POP3 (Post Office Protocol version 3), which uses port 110 to retrieve stored mail from the destination mail server.

Question 11

How do clients securely request web pages?

Answer 11

Using HTTPS (Hypertext Transfer Protocol Secure), which uses the SSL/TLS layer to encrypt requests and responses, typically communicating via port 443.

Question 12

What protocol enables secure remote administration?

Answer 12

SSH (Secure Shell) provides an encrypted channel for remote command execution and login over an unsecured network, typically using port 22.

Question 13

What is FTP (File Transfer Protocol) primarily used for?

Answer 13

It is an application layer protocol used for copying files between a client host and a server host, typically using port 21 for commands and port 20 for data.

Question 14

What is the main function of the Network (IP) Layer?

Answer 14

It moves IP-layer packets (datagrams) between hosts and routers, using IP addresses to determine routing across the internet, providing best-effort delivery.

Question 15

What is the function of the Link Layer?

Answer 15

It handles the physical interface details (cable or wireless), adding source and destination hardware addresses (MAC addresses) to packets before transferring bits onto the physical medium.

Question 16

How is a conceptual IPv4 address divided?

Answer 16

It is split into a prefix (Network ID) and a suffix (Host ID).

Question 17

What are the two current IP address standards and why was one introduced?

Answer 17

IPv4 (32-bit) and IPv6 (128-bit); IPv6 was introduced to solve the problem of eventually running out of available IPv4 addresses.

Question 18

What is the purpose of the Subnet Mask?

Answer 18

The subnet mask defines the number of bits in the prefix (Network ID) of an IP address, enabling a computer or router to determine the address of its local subnet via a bitwise AND operation.

Question 19

What is the difference between a Public and Private IP address?

Answer 19

Public IP addresses are globally unique and routable on the Internet; Private IP addresses are reserved for internal LANs and are non-routable across the public Internet.

Question 20

What is the role of a MAC Address?

Answer 20

It is the physical, globally unique 48-bit hardware address of the network adapter, used by the Link Layer for addressing within a local hop.

Question 21

Do MAC addresses change as a packet crosses the Internet?

Answer 21

Yes, the hardware source and destination addresses change for each hop between directly connected hosts or routers.

Question 22

What is the primary purpose of the DHCP system?

Answer 22

It automates host setup by dynamically assigning temporary or permanent IP addresses and delivering essential host configuration parameters (like subnet mask and gateway address).

Question 23

Why do networks often use Private IP addresses and NAT?

Answer 23

Due to the scarcity of IPv4 addresses, NAT (Network Address Translation) allows a local network using non-routable private addresses to connect to the Internet using only a single routable public IP address.

Question 24

What is the purpose of Network Address Translation (NAT)?

Answer 24

NAT solves the shortage of IPv4 addresses by allowing devices with non-routable private IP addresses to access the public Internet via a single public IP address assigned to the router.

Question 25

How does a NAT-enabled router facilitate communication outside the LAN?

Answer 25

The router acts as a single device with a single globally unique IP address, hiding the internal addressing details of the private network (LAN) from the outside world.

Question 26

What is a thick-client workstation?

Answer 26

A computer/workstation with non-volatile local storage (HDD/SSD) that stores and runs its own operating system and applications locally.

Question 27

What defines a thin-client workstation?

Answer 27

A diskless workstation with low specifications (little RAM, low CPU) that loads its operating system and runs applications centrally from a dedicated server.

Question 28

What is the primary maintenance advantage of thin-client computing?

Answer 28

It offers a single point of control for patches/updates and installation of new applications on the server, minimizing the software maintenance overhead compared to thick clients.

Question 29

How do peer-to-peer (P2P) networks operate?

Answer 29

There is an always-on server that services requests from numerous clients, and clients typically do not communicate directly with each other.

Question 30

What is the primary role of APIs (Application Programming Interfaces)?

Answer 30

APIs establish communication interfaces, such as the Websocket protocol API, which creates a persistent, full-duplex TCP connection allowing both client and server to send data simultaneously.

Question 31

How does REST map HTTP methods to database operations (CRUD)?

Answer 31

REST methods map onto CRUD operations (Create, Retrieve, Update, Delete), converting HTTP verbs like GET to SELECT (retrieve) or POST to INSERT (create).

Question 32

What are the primary risks associated with Worms and Viruses?

Answer 32

These are types of malicious software (malware) that are self-replicating and exploit vulnerabilities in code to spread, potentially creating backdoors or launching botnets

Question 33

How does a Trojan typically gain access to a computer system?

Answer 33

A Trojan is malicious software often disguised as legitimate software, and users are typically tricked into loading and executing it.

Question 34

How does a worm spread through a network?

Answer 34

Worms are self-contained programs that replicate themselves by exploiting a vulnerability in a running network application program, often without requiring explicit user interaction

Question 35

What defines a brute-force attack against a cipher like Caesar?

Answer 35

It is an attack that relies on attempting all possible keys until the plaintext is discovered; this is effective against systems (like the Caesar cipher) where the number of possible keys is too small.

Question 36

What is the goal of a Social Engineering attack?

Answer 36

Attackers use social engineering to gain a user's trust, enabling them to steal sensitive information or dupe the user into downloading or executing malware.

Question 37

What core programming vulnerability is often exploited by worms and viruses?

Answer 37

Attackers often exploit vulnerabilities in code, including defects or design flaws, in order to get a computer to execute their malicious software.

Question 38

How does a firewall use stateful inspection to prevent data interception/attacks?

Answer 38

If a firewall performs stateful inspection, it tracks active TCP connections and uses this connection information to determine if incoming packets are legitimate parts of an ongoing dialogue or bogus attempts, blocking packets that do not match.

Question 39

What capability of an application or operating system is necessary for a successful virus infection?

Answer 39

Viruses require some form of user interaction to infect a computer, as they are malicious software attached to another file (such as an email attachment) which the user must be tricked into opening.

Question 40

What is a Queue and its core principle?

Answer 40

A dynamic, ordered data structure following the FIFO (First In First Out) principle, where items are added at the rear and removed from the front.

Question 41

What are the primary operations on a Queue?

Answer 41

Enqueue (add item to rear), Dequeue (remove item from front), Peek or Top (examine the front item without removal), Is Empty, and Is Full.

Question 42

What is a Priority Queue?

Answer 42

Items are ordered by an internal priority value; the item with the highest priority is removed first, overriding the FIFO principle (unless priorities are equal).

Question 43

What is a Stack and its core principle?

Answer 43

A dynamic, ordered data structure following the LIFO (Last In First Out) principle, where additions (Push) and removals (Pop) occur only at the top.

Question 44

What is the purpose of the Call Stack in programming?

Answer 44

For Depth-First Traversal of graphs/trees, handling subroutine calls (call stack), and evaluating arithmetic expressions in Reverse Polish Notation (RPN).

Question 45

What defines a Graph?

Answer 45

A structure composed of Vertices (nodes) and Edges (arcs) that represent relationships, characterized by having no inherent root and potentially allowing loops.

Question 46

How does a Graph differ from a Tree?

Answer 46

A tree is a connected, undirected graph with no cycles; trees often define hierarchical parent-child relationships, which graphs do not inherently require.

Question 47

How are Graphs commonly represented in computer memory?

Answer 47

Using an Adjacency List (often dictionaries/hash tables) or an Adjacency Matrix (two-dimensional array).

Question 48

What is the goal of Depth-First Traversal (DFT)?

Answer 48

To traverse the graph by exploring along each branch as far as possible before backtracking; typically implemented using a Stack data structure.

Question 49

What is the goal of Breadth-First Traversal (BFT)?

Answer 49

To traverse the graph by visiting all neighboring vertices level by level; this method is used to find the shortest path (in terms of edges) and requires a Queue.

Question 50

What is Recursion?

Answer 50

A computational method where a function or procedure is defined in terms of itself; it solves a problem by continually moving toward a simpler case.

Question 51

What is the role of the Base Case in recursion?

Answer 51

It is the easiest form of the problem that stops the recursive process and returns a non-recursive solution, preventing an infinite loop.

Question 52

Why is the Call Stack crucial for recursion?

Answer 52

The call stack tracks nested calls by storing the return addresses and local variables for each recursive instance until the Base Case causes the stack to unwind.