Module 2: Networking

Question 1

What is a computer network?

Answer 1

A computer network is a system that connects numerous independent computers in order to share information (data) and resources.

Question 2

Why do networks exist?

Answer 2

Networks exist to transfer data at literal lightning speeds. They improve daily life, business, and even warfare. They also facilitate even the most mundane office tasks.

Question 3

What does a router do?

Answer 3

A router sends traffic between different networks. It’s a computer with software on it that is capable of routing traffic.

Question 4

What does a switch do?

Answer 4

A switch sends traffic between different hosts on the same network.

Question 5

What is a wireless access point?

Answer 5

A wireless access point allows hosts to connect to the network wirelessly.

Question 6

What is an IP address?

Answer 6

A unique ID for devices connecting to a network, used to send and receive information.

Question 7

What is the structure of an IPv4 address?

Answer 7

It is made up of four sections, each called an “octet”. Each octet, in binary, is comprised of eight bits, making a total of 32 bits for the IP address.

Question 8

How does binary counting work?

Answer 8

Binary counting uses multiples of two, from right to left: 1’s, 2’s, 4’s, 8’s, 16’s, etc., based on electrical signals being “ON” (1), or “OFF” (0).

Question 9

What is a subnet mask and how does it work?

Answer 9

A subnet mask identifies which portion of the IP address is the Network ID; the remainder is considered the Host ID.

Question 10

What is CIDR notation?

Answer 10

CIDR Notation is a shorthand way of representing any given IP address with its Subnet Mask. (Ex. 192 . 168 . 0 . 0 / 24) (The /24 represents the number of bits in the Subnet Mask. That is:)

Question 11

What is an APIPA?

Answer 11

Automatic Private IP Addressing (APIPA) is a DHCP failover mechanism used by all Microsoft Windows Operating Systems which assigns an address when a DHCP server is not available. This allows hosts on the same network to be able to communicate with each other in spite of not being assigned an address by a DHCP server.

Question 12

What are Loopback Addresses?

Answer 12

The address range 127.0.0.0 to 127.255.255.254 are referred to as “loopback” addresses. They allow a computer to confirm that it can use TCP/IP and allow for different programs running on the same machine to communicate with each other using IP.

Question 13

What are Private IP Addresses?

Answer 13

A specific set of IP addresses used for private network use. You’ll likely see these assigned to your personal devices whenever you are working from home or an office.

Question 14

What are Ports?

Answer 14

Ports are essentially endpoints where network connections can start and or end. Ports can be considered the “apartment number” or “suite number” in an apartment building where the apartment building is the “IP Address”.

Question 15

What are Protocols?

Answer 15

A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network.

Question 16

What is TCP?

Answer 16

(Transmission Control Protocol)
TCP is considered a “connection oriented” protocol and is used when it’s absolutely imperative that all data is successfully transmitted (for example, when sending files) at the cost of speed.

Question 17

What is UDP?

Answer 17

(User Datagram Protocol)
UDP offers best-effort delivery of data but is much quicker with less overhead.

Question 18

What is HTTP?

Answer 18

(Hypertext Transfer Protocol)
HTTP is a protocol used by your computer usually when browsing the internet. The port for HTTP is 80 (TCP).

Question 19

What is HTTPS?

Answer 19

(Hypertext Transfer Protocol Secure)
HTTPS is a secure version of HTTP. The port for HTTPS is 443 (TCP).

Question 20

What is DHCP?

Answer 20

(Dynamic Host Configuration Protocol)
DHCP is a protocol used to assign an IP address to devices when they are first connected to the network. The ports for DHCP are 67 and 68 (UDP).

Question 21

What is DNS?

Answer 21

(Domain Name System)
DNS is a protocol whose primary goal is to convert human readable domain names (such as www.google.com) to IP addresses, which computer can use and understand. The port for DNS is 53 (Both TCP and UDP).

Question 22

What is RDP?

Answer 22

(Remote Desktop Protocol)
RDP is used when remotely connecting from one computer to another to gain a remote desktop GUI. The port for RDP is 3389 (TCP).

Question 23

What is SSH?

Answer 23

(Secure Shell)
SSH is used when remotely connecting from one computer to another and spawning a command line. The port for SSH is 22 (TCP).

Question 24

What is ICMP?

Answer 24

(Internet Control Message Protocol)
ICMP is the protocol that “ping” uses. Ping is a command tool used to check if another computer is reachable on the network line. ICMP does not have a port.

Question 25

What is a MAC address?

Answer 25

A MAC (Media Access Control) address is a unique hardware identifier assigned to network interface cards (NICs) in devices like computers, smartphones, and routers, used for communication within a network.

Question 26

How is a MAC address represented?

Answer 26

MAC addresses are 48-bit hexadecimal numbers, typically represented in six pairs of characters separated by colons or hyphens (Ex: 01:23:45:67:89:AB).

Question 27

How is a MAC address assigned?

Answer 27

The first 24 bits of a MAC address (called the Organizationally Unique Identifier, or OUI) are assigned to specific manufacturers, while the remaining 24 bits are assigned by the manufacturer to each individual NIC they produce.

Question 28

At which layer of the OSI model do MAC addresses operate?

Answer 28

MAC addresses operate at Layer 2 (the Data Link Layer) of the OSI model, facilitating communication between devices on the same local network segment.

Question 29

Are MAC addresses static or dynamic?

Answer 29

While MAC addresses are typically static and permanently assigned to a NIC, they can be changed manually or programmatically using software (a process known as MAC spoofing) for various reasons, such as increased privacy or bypassing network restrictions.

Question 30

What is the OSI Model?

Answer 30

The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a communication system into seven distinct layers. Each layer plays a role in delivering content to your device.

Question 31

What is the first layer in the OSI Model?

Answer 31

Physical Layer
It involves physical mediums like fiber and twisted pair.

Question 32

What is the second layer in the OSI Model?

Answer 32

Data Link Layer
It handles communication between local devices and involves MAC Addresses.

Question 33

What is the third layer in the OSI Model?

Answer 33

Network Layer
It manages communication between separate networks and involves IP Addresses.

Question 34

What is the fourth layer in the OSI Model?

Answer 34

Transport Layer
Involves TCP/UDP ports.

Question 35

What is the fifth layer in the OSI Model?

Answer 35

Session Layer
It helps manage and maintain individual connections between a web browser’s multiple tabs and their respective web servers.

Question 36

What is the sixth layer in the OSI Model?

Answer 36

Presentation Layer
It translates data formats between applications and the network, ensuring compatibility. It handles tasks like data encryption/decryption, compression/decompression, and character encoding.

Question 37

What is the seventh layer in the OSI Model?

Answer 37

Application Layer
It facilitates communication between user applications and network services. It uses protocols like HTTP or HTTPS to request and receive data from web servers.