# Question Answer
1 What is the OSI model? A 7-layer conceptual framework for
how network communications work:
Physical, Data Link, Network,
Transport, Session, Presentation,
and Application layers.
2 What are the 7 layers of the 1-Physical, 2-Data Link, 3-Network,
OSI model in order from 4-Transport, 5-Session, 6-
bottom to top? Presentation, 7-Application.
3 What does the Physical layer Transmits raw bits over a physical
(Layer 1) do? medium; deals with cables,
switches, voltages, and signal
timing.
4 What does the Data Link layer Handles node-to-node data
(Layer 2) do? transfer, MAC addressing, error
detection, and framing between
directly connected devices.
5 What does the Network layer Manages logical addressing (IP
(Layer 3) do? addresses) and routing of packets
across multiple networks.
6 What does the Transport Provides end-to-end
layer (Layer 4) do? communication, segmentation, flow
control, and error recovery using
protocols like TCP and UDP.
7 What does the Session layer Establishes, manages, and
(Layer 5) do? terminates communication sessions
between applications.
8 What does the Presentation Translates data formats, handles
layer (Layer 6) do? encryption/decryption, and data
,# Question Answer
compression between application
and network.
9 What does the Application Provides network services directly
layer (Layer 7) do? to end-user applications (HTTP,
FTP, SMTP, DNS, etc.).
10 What is the TCP/IP model? A 4-layer model: Network Access,
Internet, Transport, and Application.
It is the practical model used on the
modern internet.
11 What is TCP? Transmission Control Protocol – a
connection-oriented Transport layer
protocol providing reliable, ordered,
error-checked delivery of data.
12 What is UDP? User Datagram Protocol – a
connectionless Transport layer
protocol that is fast but provides no
guarantee of delivery or ordering.
13 What is the difference TCP is reliable, connection-
between TCP and UDP? oriented, and uses handshaking;
UDP is faster, connectionless, and
has no delivery guarantees.
14 What is the TCP three-way SYN (client to server), SYN-ACK
handshake? (server to client), ACK (client to
server) — establishes a TCP
connection.
15 What is an IP address? A numerical label assigned to each
device on a network that uses the
Internet Protocol for
communication.
16 What is the difference IPv4 uses 32-bit addresses (e.g.,
between IPv4 and IPv6? 192.168.1.1); IPv6 uses 128-bit
addresses to accommodate far
more devices.
17 What is a MAC address? A hardware identifier assigned to a
network interface card (NIC), used
,# Question Answer
for communication at the Data Link
layer.
18 What is a subnet mask? A 32-bit number that divides an IP
address into network and host
portions (e.g., 255.255.255.0).
19 What is CIDR notation? Classless Inter-Domain Routing
notation represents a network
address and its prefix length (e.g.,
192.168.1.0/24).
20 What is a default gateway? The IP address of the router that
forwards traffic from a local network
to other networks or the internet.
21 What is DHCP? Dynamic Host Configuration
Protocol – automatically assigns IP
addresses and network
configuration to devices.
22 What is DNS? Domain Name System – translates
human-readable domain names
(e.g., google.com) into IP
addresses.
23 What is ARP? Address Resolution Protocol –
maps an IP address to a physical
(MAC) address on a local network.
24 What is NAT? Network Address Translation –
maps private IP addresses to one
or more public IP addresses for
internet communication.
25 What is a router? A Layer 3 device that forwards
packets between different networks
based on IP addressing and routing
tables.
26 What is a switch? A Layer 2 device that forwards
frames within a network based on
MAC addresses.
, # Question Answer
27 What is a hub? A Layer 1 device that broadcasts
incoming data to all ports; largely
replaced by switches.
28 What is a firewall? A security device (hardware or
software) that monitors and controls
incoming/outgoing network traffic
based on security rules.
29 What is a VPN? Virtual Private Network – creates
an encrypted tunnel over a public
network to securely connect remote
users or sites.
30 What is a VLAN? Virtual Local Area Network – a
logical segmentation of a network
at Layer 2, isolating traffic without
separate hardware.
31 What is bandwidth? The maximum rate of data transfer
across a network path, typically
measured in bits per second (bps).
32 What is latency? The time delay for data to travel
from source to destination, usually
measured in milliseconds.
33 What is a packet? A unit of data formatted for
transmission over a network,
containing header information and
payload.
34 What is a frame? A Layer 2 data unit that
encapsulates a packet with
source/destination MAC addresses
and error-checking.
35 What is encapsulation in The process of wrapping data with
networking? protocol-specific headers/trailers as
it moves down the OSI layers.
36 What is a broadcast domain? A network segment where
broadcast packets are forwarded to
1 What is the OSI model? A 7-layer conceptual framework for
how network communications work:
Physical, Data Link, Network,
Transport, Session, Presentation,
and Application layers.
2 What are the 7 layers of the 1-Physical, 2-Data Link, 3-Network,
OSI model in order from 4-Transport, 5-Session, 6-
bottom to top? Presentation, 7-Application.
3 What does the Physical layer Transmits raw bits over a physical
(Layer 1) do? medium; deals with cables,
switches, voltages, and signal
timing.
4 What does the Data Link layer Handles node-to-node data
(Layer 2) do? transfer, MAC addressing, error
detection, and framing between
directly connected devices.
5 What does the Network layer Manages logical addressing (IP
(Layer 3) do? addresses) and routing of packets
across multiple networks.
6 What does the Transport Provides end-to-end
layer (Layer 4) do? communication, segmentation, flow
control, and error recovery using
protocols like TCP and UDP.
7 What does the Session layer Establishes, manages, and
(Layer 5) do? terminates communication sessions
between applications.
8 What does the Presentation Translates data formats, handles
layer (Layer 6) do? encryption/decryption, and data
,# Question Answer
compression between application
and network.
9 What does the Application Provides network services directly
layer (Layer 7) do? to end-user applications (HTTP,
FTP, SMTP, DNS, etc.).
10 What is the TCP/IP model? A 4-layer model: Network Access,
Internet, Transport, and Application.
It is the practical model used on the
modern internet.
11 What is TCP? Transmission Control Protocol – a
connection-oriented Transport layer
protocol providing reliable, ordered,
error-checked delivery of data.
12 What is UDP? User Datagram Protocol – a
connectionless Transport layer
protocol that is fast but provides no
guarantee of delivery or ordering.
13 What is the difference TCP is reliable, connection-
between TCP and UDP? oriented, and uses handshaking;
UDP is faster, connectionless, and
has no delivery guarantees.
14 What is the TCP three-way SYN (client to server), SYN-ACK
handshake? (server to client), ACK (client to
server) — establishes a TCP
connection.
15 What is an IP address? A numerical label assigned to each
device on a network that uses the
Internet Protocol for
communication.
16 What is the difference IPv4 uses 32-bit addresses (e.g.,
between IPv4 and IPv6? 192.168.1.1); IPv6 uses 128-bit
addresses to accommodate far
more devices.
17 What is a MAC address? A hardware identifier assigned to a
network interface card (NIC), used
,# Question Answer
for communication at the Data Link
layer.
18 What is a subnet mask? A 32-bit number that divides an IP
address into network and host
portions (e.g., 255.255.255.0).
19 What is CIDR notation? Classless Inter-Domain Routing
notation represents a network
address and its prefix length (e.g.,
192.168.1.0/24).
20 What is a default gateway? The IP address of the router that
forwards traffic from a local network
to other networks or the internet.
21 What is DHCP? Dynamic Host Configuration
Protocol – automatically assigns IP
addresses and network
configuration to devices.
22 What is DNS? Domain Name System – translates
human-readable domain names
(e.g., google.com) into IP
addresses.
23 What is ARP? Address Resolution Protocol –
maps an IP address to a physical
(MAC) address on a local network.
24 What is NAT? Network Address Translation –
maps private IP addresses to one
or more public IP addresses for
internet communication.
25 What is a router? A Layer 3 device that forwards
packets between different networks
based on IP addressing and routing
tables.
26 What is a switch? A Layer 2 device that forwards
frames within a network based on
MAC addresses.
, # Question Answer
27 What is a hub? A Layer 1 device that broadcasts
incoming data to all ports; largely
replaced by switches.
28 What is a firewall? A security device (hardware or
software) that monitors and controls
incoming/outgoing network traffic
based on security rules.
29 What is a VPN? Virtual Private Network – creates
an encrypted tunnel over a public
network to securely connect remote
users or sites.
30 What is a VLAN? Virtual Local Area Network – a
logical segmentation of a network
at Layer 2, isolating traffic without
separate hardware.
31 What is bandwidth? The maximum rate of data transfer
across a network path, typically
measured in bits per second (bps).
32 What is latency? The time delay for data to travel
from source to destination, usually
measured in milliseconds.
33 What is a packet? A unit of data formatted for
transmission over a network,
containing header information and
payload.
34 What is a frame? A Layer 2 data unit that
encapsulates a packet with
source/destination MAC addresses
and error-checking.
35 What is encapsulation in The process of wrapping data with
networking? protocol-specific headers/trailers as
it moves down the OSI layers.
36 What is a broadcast domain? A network segment where
broadcast packets are forwarded to
