Inno 3.1 Protocols

Question 1

What is TCP (Transmission Control Protocol)?

Answer 1

TCP is a connection-oriented protocol that ensures reliable, ordered, and error-checked delivery of data between applications.

It establishes a connection before transferring data and confirms delivery using acknowledgments. It’s widely used for applications where accuracy is critical, such as web pages, emails, and file transfers. TCP is slower than UDP but more reliable. Examples of protocols using TCP include HTTP, FTP, and SMTP.

RELIABLE, ORDERD, ERROR-CHECKED, CONNECTION

Question 2

What is UDP (User Datagram Protocol)?

Answer 2

UDP is a connectionless protocol that sends data without guaranteeing delivery, order, or error correction. It is faster than TCP and is ideal for real-time applications like video streaming, gaming, and VoIP, where speed is more important than perfect accuracy. Because it doesn’t establish connections or wait for acknowledgments, it’s lightweight and low-latency. However, it is less reliable and can result in lost or out-of-order packets.

CONNECTIONLESS, NOT IN ORDER

Question 3

What is SMTP (Simple Mail Transfer Protocol)?

Answer 3

SMTP is a protocol used for sending emails between servers. It works over TCP (usually port 25, 587, or 465 with SSL) and is responsible for the delivery of messages from a client to a mail server or between mail servers. SMTP is a push protocol — it only sends messages, not retrieves them. Email clients usually use it in combination with POP3 or IMAP for receiving mail.

MAIL, JUST SEND

Question 4

What is FTP (File Transfer Protocol)?

Answer 4

FTP is a protocol used to transfer files between a client and server over a network. It operates over TCP (typically ports 20 and 21) and supports basic authentication with username and password.

FTP allows both uploading and downloading of files but transmits data in plain text, making it insecure by modern standards. For secure transfers, SFTP or FTPS is recommended.

SUPPORT BASIC AUTH, ALLOWS UPLOADING AND DOWNLOADING, PLAIN TEXT

Question 5

What is SFTP (SSH File Transfer Protocol)?

Answer 5

A: SFTP is a secure file transfer protocol that operates over SSH (port 22). Unlike FTP, it encrypts both commands and data, protecting sensitive information during transmission. SFTP provides secure file access, transfer, and management functionalities. It is widely used in enterprise environments where data security is critical.

NOT A VERSION ON SFTP

SFTP is not a version of FTP—it is a completely separate protocol.

Question 6

What is HTTP (Hypertext Transfer Protocol)?

Answer 6

HTTP is the foundation of data communication on the web, used to transmit web pages and APIs.

It is a stateless, request-response protocol running over TCP (usually port 80 or 443 for HTTPS). HTTP defines methods like GET, POST, PUT, and DELETE to interact with resources.

While simple and widely adopted, it is limited for real-time or bidirectional communication. HTTPS (HTTP Secure) adds encryption via TLS/SSL.

Question 7

What are WebSockets?

Answer 7

A: WebSockets provide a full-duplex communication channel over a single TCP connection.

Unlike HTTP, which is request/response-based,

WebSockets allow both the client and server to send data anytime, making them ideal for real-time applications like chats, games, and live feeds.

They start as an HTTP connection and then upgrade to the WebSocket protocol.

WebSockets are more efficient for frequent, lightweight messaging compared to repeated HTTP requests.

SEND DATA ANY TIME

Question 8

What is gRPC?

Answer 8

gRPC is a high-performance, open-source RPC (Remote Procedure Call) framework developed by Google.

It uses HTTP/2 as its transport protocol and Protocol Buffers (protobuf) as the interface definition language and message format.

gRPC enables client-server communication in a more efficient, strongly-typed, and language-agnostic way. It supports streaming, bi-directional communication, and is ideal for microservices. Compared to REST, gRPC is more compact and faster.

PROTOBUFFS AS INTERFACE DEFINITION LANGUAGE

Question 9

What is AMQP (Advanced Message Queuing Protocol)?

Answer 9

AMQP is a protocol designed for message-oriented middleware, enabling secure and reliable communication between distributed systems.

It supports features like message queuing, routing, publish/subscribe, and delivery acknowledgments.

AMQP is used in brokers like RabbitMQ and is ideal for enterprise messaging and decoupled architectures. It ensures messages are not lost and can be processed even if the receiver is temporarily offline.

Question 10

What is MQTT (Message Queuing Telemetry Transport)?

Answer 10

MQTT is a lightweight messaging protocol designed for constrained devices and low-bandwidth, high-latency networks. It follows a publish/subscribe model and is commonly used in IoT (Internet of Things) scenarios.

MQTT is optimized for small payloads and power efficiency, making it ideal for sensors, smart home devices, and mobile applications. It uses TCP (typically port 1883) and supports persistent sessions and QoS levels.

SMALL PAYLOAD, POWER EFFICIENCY

Question 11

What are the main differences between TCP and UDP?

Answer 11

TCP is connection-oriented, reliable, and ensures data arrives in order, making it suitable for web, email, and file transfer. UDP is connectionless, faster, and does not guarantee delivery or order, making it ideal for real-time applications like video calls or gaming.

Question 12

In which scenarios would you prefer UDP over TCP?

Answer 12

You would prefer UDP in real-time applications such as video streaming, VoIP, or online gaming, where speed and low latency are more important than perfect reliability or packet order.

Question 13

How does SFTP differ from FTP?

Answer 13

SFTP uses SSH for encryption and operates on a single secure connection (usually port 22), while FTP transmits data in plain text and requires separate control and data channels. SFTP is much more secure and modern.

Question 14

Why is HTTP considered a stateless protocol?

Answer 14

Because each HTTP request is independent — the server does not retain any information about previous requests. Any necessary state (like sessions) must be maintained client-side (e.g., via cookies or tokens).

Question 15

How do WebSockets improve upon HTTP for real-time communication?

Answer 15

WebSockets provide a persistent, bidirectional communication channel over a single TCP connection, eliminating the need for repeated requests (polling).

This reduces latency and overhead for real-time updates like chat, notifications, or dashboards.

Question 16

What are some use cases where gRPC is more suitable than REST?

Answer 16

gRPC is more efficient for microservices, internal service-to-service communication, and performance-critical applications due to its support for binary format, streaming, and strong typing with Protocol Buffers.

BINARY FORMAT AND STRONG TYPING WITH PROTOCOL BUFFERS

Question 17

What is the role of a message broker in protocols like AMQP and MQTT?

Answer 17

The broker handles routing, queuing, and delivering messages between publishers and subscribers.

It enables decoupling of services and ensures reliable communication even if consumers are temporarily offline.

Question 18

How does MQTT ensure lightweight communication for IoT devices?

Answer 18

MQTT minimizes bandwidth usage with small headers, uses TCP for stability, and allows clients to subscribe to only the topics they care about. It also supports different Quality of Service (QoS) levels for message delivery guarantees.

Question 19

What does it mean that AMQP supports message acknowledgments?

Answer 19

AMQP allows consumers to confirm when messages are successfully processed. If a message is not acknowledged, the broker can re-deliver it, ensuring reliability in communication.

Question 20

What is a common security risk with FTP, and how can it be mitigated?

Answer 20

FTP transmits data and credentials in plain text, making it vulnerable to interception. This can be mitigated by using secure alternatives like SFTP or FTPS, which encrypt communication.

Question 21

How does gRPC handle communication efficiency compared to REST?

Answer 21

gRPC uses HTTP/2 for multiplexed streams and binary serialization (Protocol Buffers), making it significantly more efficient in terms of speed and payload size than REST with JSON over HTTP/1.1.

Question 22

What transport protocol is used by WebSockets and MQTT?

Answer 22

Both WebSockets and MQTT use TCP as their transport protocol, ensuring reliable delivery of messages.

Question 23

What is the difference between push and pull models in messaging protocols?

Answer 23

A: In a push model (like SMTP), the sender initiates the message delivery. In a pull model (like POP3/IMAP), the receiver fetches messages. Publish/subscribe protocols like MQTT allow for event-driven communication where messages are pushed to all subscribers of a topic.

Question 24

Which port does HTTP and HTTPS use by default?

Answer 24

HTTP uses port 80 by default, while HTTPS (secured with TLS/SSL) uses port 443.

Question 25

Why is TCP preferred for file transfers instead of UDP?

Answer 25

TCP ensures data integrity with acknowledgments, retransmissions, and packet ordering, which are essential for accurate file transfers — unlike UDP, which does not guarantee delivery.

Question 26

What does connection-oriented mean in the context of TCP?

Answer 26

It means a reliable session is established before data is transmitted. The client and server perform a 3-way handshake to agree on communication before exchanging data.

Question 27

Can UDP be used securely?

Answer 27

Yes, but not by default. UDP itself doesn’t support encryption, but security can be added with external protocols like **DTLS** (Datagram TLS) or through VPN tunnels.

Question 28

What is the purpose of the 3-way handshake in TCP?

Answer 28

It establishes a reliable connection by exchanging SYN, SYN-ACK, and ACK packets, ensuring both sides are ready to transmit and receive data.

Question 29

What is the difference between active and passive FTP modes?

Answer 29

In active mode, the server initiates the data connection to the client. In passive mode, the client initiates both control and data connections, which works better behind firewalls.

Question 30

What encryption is used in SFTP?

Answer 30

SFTP uses SSH (Secure Shell) for encryption, ensuring secure authentication and data transmission over port 22.

Question 31

What is the role of headers in HTTP communication?

Answer 31

HTTP headers carry metadata such as content type, authentication tokens, user agents, and caching instructions, helping the server understand how to process the request.

Question 32

How does WebSocket handle connection lifecycle?

Answer 32

WebSockets begin as an HTTP connection, then "upgrade" via a handshake to a persistent, full-duplex WebSocket connection, which remains open until explicitly closed by either party.

Question 33

What is backpressure in WebSocket or gRPC streaming?

Answer 33

Backpressure is a mechanism to prevent a fast sender from overwhelming a slower receiver by **pausing or slowing down the flow of data** when the receiver can’t keep up.

Question 34

What is a proto file in gRPC?

Answer 34

**A .proto file defines the structure of messages and the services in Protocol Buffers syntax, which gRPC** uses to auto-generate client and server code in multiple languages.

Question 35

What protocol does gRPC use under the hood?

Answer 35

gRPC uses **HTTP/2** as its transport protocol, which supports multiplexing, streaming, and efficient binary framing.

Question 36

What messaging pattern does MQTT follow?

Answer 36

MQTT uses the **publish/subscribe** pattern, where clients publish messages to topics, and others subscribe to those topics to receive updates in real time.

Question 37

How does QoS (Quality of Service) work in MQTT?

Answer 37

MQTT has 3 levels: QoS 0: At most once (no delivery guarantee) QoS 1: At least once (may be duplicated) QoS 2: Exactly once (no duplication)

Question 38

How does AMQP differ from MQTT in message delivery?

Answer 38

AMQP is more feature-rich and enterprise-focused, supporting complex routing, message durability, and delivery acknowledgment; MQTT is simpler and designed for constrained IoT devices.

Question 39

Can WebSockets work over HTTPS?

Answer 39

Yes. Secure WebSockets use the **wss://** protocol and run over port 443, enabling encrypted, real-time communication through firewalls and proxies. WEBSOCKETS CAN BE ENCRYPTED

Question 40

Why is Protocol Buffers (protobuf) better for gRPC than JSON?

Answer 40

Protobuf is compact and **binary**-encoded, which reduces payload size and improves parsing speed — ideal for performance-critical services.

Question 41

What is the difference between REST and gRPC in terms of data format?

Answer 41

REST typically uses JSON (human-readable), while gRPC uses Protocol Buffers (binary and schema-based), resulting in better performance and smaller messages.

Question 42

What is the OSI Model and why is it important?

Answer 42

The OSI (**Open Systems Interconnection**) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into 7 layers. It helps understand how data travels through networks and separates concerns between hardware, transport, and applications.

Question 43

What are the 7 layers of the OSI model (from top to bottom)?

Answer 43

Application Presentation Session Transport Network Data Link Physical

Question 44

What are some real-world protocols used in the Transport layer of the OSI model?

Answer 44

**TCP and UDP operate at the Transport layer (Layer 4)**. They handle data segmentation, flow control, and delivery reliability.

Question 45

Which layer is responsible for routing data between devices on different networks?

Answer 45

The Network layer (Layer 3), where IP (Internet Protocol) operates, is responsible for routing, addressing, and packet forwarding.

Question 46

Which layer is responsible for MAC addresses and Ethernet?

Answer 46

The Data Link layer (Layer 2) deals with physical addressing (MAC), framing, and error detection for local network communication.

Question 47

What does the Physical layer (Layer 1) handle?

Answer 47

It deals with the actual physical medium (cables, radio waves, voltages), and the transmission and reception of raw bits (0s and 1s) over a physical medium.

Question 48

What is the difference between the TCP/IP model and the OSI model?

Answer 48

TCP/IP has 4 layers: Application, Transport, Internet, and Network Access. It is the practical, real-world model used on the internet, while OSI is more of a theoretical reference model with 7 layers.

Question 49

Which protocols operate in the Application layer of the OSI model?

Answer 49

HTTP, FTP, SMTP, DNS, MQTT, and others — these are protocols that provide services directly to user applications.

Question 50

How does data flow through the OSI model layers?

Answer 50

When sending data, it flows from Layer 7 (Application) down to Layer 1 (Physical). On the receiving side, it flows from Layer 1 up to Layer 7.

Question 51

What is encapsulation in networking?

Answer 51

**Encapsulation is the process of wrapping data with protocol-specific headers** (and sometimes footers) as it moves down the OSI layers, forming a complete packet ready for transmission.

Question 52

What are ports in networking and which layer uses them?

Answer 52

Ports are logical endpoints used to identify specific processes or services on a host. They are used in the Transport layer (Layer 4) with TCP/UDP.

Question 53

What is the difference between an IP address and a MAC address?

Answer 53

An IP address (Layer 3) identifies a device on a network globally; a MAC address (Layer 2) uniquely identifies a device on the local network segment.

Question 54

What is ARP (Address Resolution Protocol) used for?

Answer 54

ARP is used to map IP addresses (Layer 3) to MAC addresses (Layer 2) in a local network. It's essential for proper packet delivery on Ethernet-based networks.

Question 55

What protocol is responsible for IP packet fragmentation and routing?

Answer 55

IP (Internet Protocol) in the Network layer handles packet fragmentation, addressing, and routing between networks.

Question 56

What is a socket in networking?

Answer 56

**A socket is an endpoint for sending or receiving data across a network**. It's typically defined by an IP address and port number (e.g., 192.168.1.10:80).

Question 57

What is the purpose of DNS?

Answer 57

DNS (Domain Name System) resolves human-readable domain names (like google.com) into IP addresses that computers use to route traffic.

Question 58

What is the purpose of TLS in protocols like HTTPS?

Answer 58

TLS (Transport Layer Security) provides encryption, integrity, and authentication over TCP, commonly used in HTTPS to secure web communication.

Question 59

Why do we need both TCP and IP?

Answer 59

IP handles addressing and routing (where packets go), while TCP ensures that the data arrives completely and in the correct order (how it arrives). Together, they form the basis of reliable internet communication.

Question 60

What’s the difference between a frame, a packet, and a segment?

Answer 60

Frame (Layer 2): includes MAC addresses and data link info. Packet (Layer 3): includes IP header and payload. Segment (Layer 4): includes TCP/UDP header and data.

Question 61

What happens when you type a URL in your browser?

Answer 61

DNS resolves the domain to an IP address TCP connection is established (3-way handshake) TLS handshake (if HTTPS) HTTP request is sent Server responds Browser renders the content

Question 62

What is the main difference between POP3 and IMAP

Answer 62

POP3 downloads emails and often deletes them from the server, while IMAP keeps emails on the server and syncs changes across devices. POP3 DOWNLOADS AND DELETS AND WHILE IMAP KEEPS IT ON THE SERVER

Question 63

Why is IMAP better for accessing email from multiple devices?

Answer 63

Because IMAP syncs email folders and statuses (read, deleted, etc.) with the server, allowing consistent access across all devices.

Question 64

What is POP3?

Answer 64

POP3 (Post Office Protocol version 3) is a protocol used to download emails from a server to one device, usually removing them from the server afterward. POP3 downloads emails to one device and usually deletes them from the server, so emails are stored locally and not synced across devices.

Question 65

What is IMAP?

Answer 65

IMAP (Internet Message Access Protocol) is a protocol that allows you to access and manage your emails directly on the mail server from multiple devices. IMAP keeps emails on the server and syncs them across all your devices, including folders and read/unread status.