Host to Host

Question 1

Which OSI layers are mainly involved in Host-to-Host communication?

Answer 1

Network (Layer 3), Transport (Layer 4), and Session (Layer 5)

Question 2

Q2: What is the main function of the Network layer?

Answer 2

Logical addressing (IP), routing, and path determination

Question 3

Q3: What protocols operate at the Network layer?

Answer 3

IP and ICMP

Question 4

Q4: What is the main function of the Transport layer?

Answer 4

Ensures reliable (TCP) or unreliable (UDP) delivery of data

Question 5

Q5: What protocols operate at the Transport layer?

Answer 5

TCP (reliable), UDP (unreliable)

TCP – Transmission Control Protocol
Purpose: TCP is a transport layer protocol used for reliable data transmission between computers on a network.

Key Features:

Ensures reliable and ordered delivery of data.

Connection-oriented: A connection is established before data is transferred.

Uses acknowledgments (ACKs) to confirm receipt of data.

Example: When you load a website (HTTP over TCP), the data must arrive in order and without errors.

UDP – User Datagram Protocol
Purpose: UDP is another transport layer protocol like TCP, but it is connectionless and unreliable.

Key Features:

Faster than TCP, but no guarantee that data will arrive or be in order.

No acknowledgments.

Example: Used in live video streaming, online gaming, or VoIP, where speed is more important than perfect reliability.

Question 6

Q6: Explain the TCP three-way handshake.

Answer 6

1. SYN from client
2. SYN-ACK from server
3. ACK from client
4. SYN from client
   SYN = Synchronize

Sent by the client to the server to start a TCP connection.

It’s basically saying: “I want to start communication and synchronize sequence numbers.”

2. SYN-ACK from server
   SYN-ACK = Synchronize-Acknowledge

Sent by the server to the client after receiving the SYN.

It means: “I acknowledge your request to start the connection (ACK), and I also want to synchronize my sequence numbers with you (SYN).”

3. ACK from client
   ACK = Acknowledge

Sent by the client back to the server.

It means: “I received your SYN-ACK, and now the connection is established.”

Question 7

Q7: Is TCP connection-oriented or connectionless?

Answer 7

Connection-oriented

Question 8

Q8: Is UDP connection-oriented or connectionless?

Answer 8

A8: Connectionless

Question 9

Q9: Name some common TCP use cases.

Answer 9

A9: Web (HTTP), Email (SMTP)

Question 10

Q10: Name some common UDP use cases.

Answer 10

Streaming, VoIP, DNS

Question 11

What is an IP address?

Answer 11

A 32-bit logical address assigned to devices on a network

Question 12

Q12: What is the purpose of port numbers?

Answer 12

Identify specific applications or services on a host

Question 13

Q13: What port does HTTP use?

Answer 13

Port 80

Question 14

Q14: What port does DNS use?

Answer 14

Port 53

Question 15

Q15: What port does FTP use?

Answer 15

Port 21

Question 16

Q16: What port does DHCP use?

Answer 16

Ports 67 and 68

Question 17

Q17: What protocol resolves IP addresses to MAC addresses?

Answer 17

ARP (Address Resolution Protocol)

Question 18

Q18: What is TTL in an IP packet?

Answer 18

Time to Live, limits the lifespan of a packet

Question 19

Q19: What tool is used to check connectivity using ICMP?

Answer 19

ping

Question 20

Q20: What does the tracert (Windows) or traceroute (Linux) command do?

Answer 20

Traces the path packets take to reach a destination

Question 21

Q21: What is segmentation in networking?

Answer 21

Dividing large messages into smaller segments for transmission

Question 22

Q22: What does DHCP do?

Answer 22

: Assigns IP addresses dynamically to devices

Question 23

Q23: What layer manages sessions?

Answer 23

Session Layer (Layer 5)

Question 24

Q24: What protocol is used to transfer files?

Answer 24

FTP (File Transfer Protocol)

Question 25

Q25: Which OSI layer provides error detection at the frame level?

Answer 25

Data Link Layer (Layer 2)

Question 26

Q26: Which device separates broadcast domains?

Answer 26

Router

Question 27

Q27: What layer does a switch operate at?

Answer 27

Data Link Layer (Layer 2)

Question 28

Q28: What is encapsulation?

Answer 28

Wrapping data with protocol-specific headers and trailers

Question 29

Q29: Which OSI layer adds MAC addresses?

Answer 29

Data Link Layer (Layer 2)

Question 30

Q30: Which OSI layer adds IP addresses?

Answer 30

Network Layer (Layer 3)

Question 31

Q31: Which OSI layer adds TCP/UDP headers?

Answer 31

Transport Layer (Layer 4)

Question 32

Q32: What is the binary form of 192 in IPv4?

Answer 32

11000000

Question 33

Q33: What does ICMP do?

Answer 33

Sends control messages like errors and diagnostics

Question 34

Q34: What is ARP used for?

Answer 34

Mapping IP addresses to MAC addresses

Question 35

Q35: Is ICMP used to assign IP addresses?

Answer 35

No

Question 36

Q36: Which OSI layer handles encryption and decryption?

Answer 36

Presentation Layer (Layer 6)

Question 37

What command shows IP configuration on Windows?

Answer 37

ipconfig

Question 38

Q38: What command shows IP configuration on Linux?

Answer 38

ifconfig

Question 39

Q39: What is the purpose of ACK in TCP?

Answer 39

Acknowledges receipt of data

Question 40

What is the default subnet mask for Class C?

Answer 40

255.255.255.0

Question 41

What is the default subnet mask for Class A?

Answer 41

255.0.0.0

Question 42

Q42: What does NIC stand for?

Answer 42

Network Interface Card

Question 43

Q43: What is the function of DNS?

Answer 43

Resolves domain names to IP addresses

Question 44

What protocol does DHCP use to communicate?

Answer 44

UDP

Question 45

What protocol does FTP use to communicate?

Answer 45

TCP

Question 46

What is a common use for UDP in networking?

Answer 46

Streaming video and audio

Question 47

What layer of the OSI model does IP operate at?

Answer 47

Network Layer (Layer 3)

Question 48

What is the role of the Session layer?

Answer 48

Establishes, manages, and terminates communication sessions

Question 49

Q49: What happens during encapsulation?

Answer 49

Data is wrapped with headers/trailers as it moves down the OSI layers

Question 50

Q50: What protocol is responsible for error reporting in networks?

Answer 50

ICMP

Question 51

Which OSI layer is responsible for reliable transmission between two devices? A. Network B. Data Link C. Transport D. Physical

Answer 51

Answer: c

Question 52

What protocol is used by the transport layer to provide reliable communication? A. IP B. TCP C. UDP D. ICMP

Answer 52

Answer: b

Question 53

Which layer of the OSI model assigns logical addressing such as IP addresses? A. Data Link B. Network C. Transport D. Session

Answer 53

Answer: b

Question 54

Which protocol is connectionless and does not guarantee delivery? A. TCP B. FTP C. UDP D. SMTP

Answer 54

Answer: c

Question 55

Which command is used to check DNS resolution from a Windows PC? A. ping B. tracert C. ipconfig D. nslookup

Answer 55

Answer: d

Question 56

What is the purpose of the ARP protocol? A. Assign IP addresses B. Resolve IP addresses to MAC addresses C. Route packets between networks D. Encrypt data for secure transmission

Answer 56

Answer: b

Question 57

Which OSI layer is responsible for path determination and logical addressing? A. Transport B. Network C. Data Link D. Session

Answer 57

Answer: b

Question 58

What is the default subnet mask for a Class C IP address? A. 255.0.0.0 B. 255.255.0.0 C. 255.255.255.0 D. 255.255.255.255

Answer 58

Answer: c

Question 59

Which device operates primarily at Layer 2 of the OSI model? A. Router B. Switch C. Firewall D. Modem

Answer 59

Answer: b

Question 60

What is the function of the three-way handshake in TCP communication? A. Encrypt data B. Establish a reliable connection C. Assign IP addresses D. Resolve domain names

Answer 60

Answer: b

Question 61

Which OSI layer breaks data into segments? A. Session B. Transport C. Network D. Data Link

Answer 61

Answer: b

Question 62

Which OSI layer provides services like data encryption and compression? A. Application B. Presentation C. Transport D. Network

Answer 62

Answer: b

Question 63

Which layer is responsible for end-to-end communication and error recovery? A. Network B. Transport C. Data Link D. Physical

Answer 63

Answer: b

Question 64

What is the purpose of the MAC address in networking? A. Identify devices on the internet B. Identify network topology C. Identify devices on a local network D. Assign dynamic IPs

Answer 64

Answer: c

Question 65

Which command can you use to view a device’s IP address on Windows? A. ifconfig B. ipconfig C. traceroute D. route

Answer 65

Answer: b

Question 66

Which protocol helps determine the MAC address of a known IP address? A. DHCP B. DNS C. ARP D. ICMP

Answer 66

Answer: c

Question 67

Which transport layer protocol is used by DNS? A. TCP B. UDP C. IP D. ICMP

Answer 67

Answer: b

Question 68

What is a socket composed of? A. IP address and subnet mask B. MAC address and IP address C. IP address and port number D. MAC address and port number

Answer 68

Answer: c

Question 69

What is encapsulation in networking? A. Removing headers B. Sending encrypted data C. Wrapping data with protocol-specific headers and trailers D. Compressing data

Answer 69

Answer: c

Question 70

Which OSI layer is responsible for device-to-device delivery on the same network? A. Network B. Data Link C. Transport D. Physical

Answer 70

Answer: b

Question 71

Which layer is responsible for converting data into electrical signals? A. Network B. Transport C. Physical D. Data Link

Answer 71

Answer: c

Question 72

What does TCP use to establish a reliable connection? A. A two-way handshake B. Encryption C. IP addressing D. A three-way handshake

Answer 72

Answer: d

Question 73

Which layer does IP operate at? A. Physical B. Data Link C. Network D. Transport

Answer 73

Answer: c

Question 74

What does DNS stand for? A. Data Network Switch B. Dynamic Network Server C. Domain Name System D. Digital Number System

Answer 74

Answer: c

Question 75

What does DHCP provide? A. Security B. IP address management C. Email services D. File transfers

Answer 75

Answer: b

Question 76

Which protocol allows you to send messages and errors about network operations? A. ICMP B. ARP C. DNS D. FTP

Answer 76

Answer: a

Question 77

Which number represents the well-known port range? A. 1024-49151 B. 0-1023 C. 49152-65535 D. 10000-20000

Answer 77

Answer: b

Question 78

Which device uses MAC addresses to forward traffic? A. Router B. Firewall C. Switch D. Modem

Answer 78

Answer: c

Question 79

What type of address does a router use to forward packets? A. MAC B. Port C. IP D. URL

Answer 79

Answer: c

Question 80

Which protocol helps match domain names to IP addresses? A. FTP B. ARP C. DNS D. TCP

Answer 80

Answer: c

Question 81

Which OSI layer initiates the communication session between devices? A. Application B. Session C. Presentation D. Transport

Answer 81

Answer: b

Question 82

Which layer handles the syntax and format of the data? A. Network B. Presentation C. Application D. Data Link

Answer 82

Answer: b

Question 83

What port number does HTTP use by default? A. 443 B. 22 C. 80 D. 25

Answer 83

Answer: c

Question 84

What port number does HTTPS use? A. 21 B. 80 C. 53 D. 443

Answer 84

Answer: d

Question 85

What is the function of the Physical layer in the OSI model? A. Logical addressing B. Path determination C. Bit transmission over media D. Packet routing

Answer 85

Answer: c

Question 86

Which protocol ensures data is sent in sequence and retransmits lost data? A. UDP B. TCP C. ARP D. FTP

Answer 86

Answer: b

Question 87

What is segmentation in networking? A. Breaking data into packets B. Dividing data into MAC frames C. Splitting the physical cable D. Creating multiple sessions

Answer 87

Answer: a

Question 88

Which device typically operates at the Network layer? A. Hub B. Router C. Switch D. Repeater

Answer 88

Answer: b

Question 89

What layer does FTP operate at in the OSI model? A. Network B. Transport C. Application D. Session

Answer 89

Answer: c

Question 90

What is the purpose of a port number in communication? A. It defines the subnet B. It tracks MAC addresses C. It identifies applications/services D. It encrypts the data

Answer 90

Answer: c

Question 91

Which layer is responsible for retransmitting lost segments? A. Network B. Data Link C. Transport D. Session

Answer 91

Answer: c

Question 92

What does ICMP stand for? A. Internet Control Message Protocol B. Internal Connection Management Protocol C. Internet Communication Mapping Protocol D. Internal Control Message Platform

Answer 92

Answer: a

Question 93

Which OSI layer handles flow control and congestion avoidance? A. Network B. Data Link C. Transport D. Session

Answer 93

Answer: c

Question 94

Which protocol uses port 53? A. FTP B. DNS C. HTTP D. DHCP

Answer 94

Answer: b

Question 95

Which protocol assigns IP addresses dynamically to clients? A. DNS B. TCP C. DHCP D. ARP

Answer 95

Answer: c

Question 96

Which type of address is burned into a device’s NIC? A. IP address B. MAC address C. Port number D. Subnet address

Answer 96

Answer: b

Question 97

What is the result of successful DNS resolution? A. MAC address B. IP address C. Port number D. Session ID

Answer 97

Answer: b

Question 98

Which protocol is best suited for streaming services? A. TCP B. UDP C. ICMP D. FTP

Answer 98

Answer: b

Question 99

Which command-line tool sends ICMP Echo Requests to test connectivity? A. nslookup B. ipconfig C. ping D. netstat

Answer 99

Answer: c

Question 100

Which OSI layer ensures the recipient can properly interpret data (e.g., format, encryption)? A. Session B. Network C. Presentation D. Transport

Answer 100

Answer: c