5 Most Common Networking Interview Questions You Must Know (2025)

Summary

This video covers five essential networking interview questions that every IT professional should be prepared for. The topics range from basic networking concepts like the OSI model and TCP vs UDP protocols to more practical questions such as the differences between IP and MAC addresses, and how data communication methods like unicasting and broadcasting work. Additionally, a scenario-based question explores the step-by-step process of what happens when you visit a website for the first time. With over 18 years of experience in IT, the presenter aims to provide clear and concise answers to help viewers excel in networking interviews.

Takeaways

• 😀 The OSI model is a seven-layer framework that helps explain how data is transferred over networks, with each layer performing specific functions (e.g., Application, Transport, Network).
• 😀 Understanding the differences between TCP and UDP is essential: TCP is connection-oriented and reliable, while UDP is connectionless and faster but not guaranteed to deliver data reliably.
• 😀 An IP address is a logical address assigned to devices on a network, whereas a MAC address is a permanent, physical address embedded in the device's network interface card (NIC).
• 😀 Networking communication methods like unicasting, anycasting, multicasting, and broadcasting define how data is sent across the network, with different uses depending on the scenario.
• 😀 Unicasting refers to one-to-one communication between a sender and a receiver, while broadcasting sends data to all devices in the network.
• 😀 Anycasting involves sending data from one sender to the nearest or most efficient receiver, often used in CDN for fast content delivery.
• 😀 Multicasting is a one-to-many communication method where data is sent to a specific group of receivers, often used in corporate live streams or webinars.
• 😀 When typing 'www.google.com' in a browser for the first time, a series of steps occur: DNS resolution, TCP connection establishment, TLS handshake, HTTP request and response, server processing, and rendering of the page.
• 😀 The first step in accessing a website is DNS resolution, where the browser queries the DNS server to get the IP address of the domain name.
• 😀 Security protocols like TLS/SSL are used during the connection to HTTPS websites to ensure secure communication, involving certificate exchange and trust validation between the server and browser.

Q & A

What is the OSI model and how does it relate to networking?

The OSI model is a conceptual framework that standardizes the functions of a network into seven layers: Application, Presentation, Session, Transport, Network, Data Link, and Physical. It helps in understanding how data travels across a network, from user interaction to physical transmission over a medium.

Can you briefly describe the function of each layer in the OSI model?

Sure! The seven layers are as follows: 1) **Application Layer** - Interacts with end-user software. 2) **Presentation Layer** - Translates data into a readable format. 3) **Session Layer** - Manages communication sessions. 4) **Transport Layer** - Ensures reliable data transfer. 5) **Network Layer** - Routes data packets using IP addresses. 6) **Data Link Layer** - Manages error detection and frame-level transmission. 7) **Physical Layer** - Handles actual data transmission over hardware.

What is the difference between TCP and UDP?

TCP (Transmission Control Protocol) is connection-oriented, ensuring reliable, ordered, and error-free data transmission. UDP (User Datagram Protocol) is connectionless, offering faster transmission but without reliability, sequencing, or error correction.

In what scenarios would you prefer TCP over UDP?

TCP is preferred for applications where reliability is critical, such as web browsing, email, or file transfers. It guarantees data delivery, ensuring correct sequence and error recovery.

What are IP addresses and MAC addresses, and how do they differ?

An IP address is a logical address assigned to a device in a network, used to route data. A MAC address is a unique physical address embedded in a device's network interface card (NIC), used for data transfer within a local network. IP addresses can change, but MAC addresses are permanent.

How does an IP address differ from a MAC address in terms of functionality?

An IP address identifies a device on a network and operates at the Network Layer (Layer 3), while a MAC address identifies a device's hardware network interface at the Data Link Layer (Layer 2). IP addresses can be dynamic, while MAC addresses are fixed.

What is unicast, and how is it different from other communication types?

Unicast is a one-to-one communication method where data is sent from one sender to one specific receiver. Unlike broadcast or multicast, it targets a single recipient and is commonly used in most network communications, such as web browsing.

Explain the concept of anycast and provide an example of its use.

Anycast involves sending data from one sender to the nearest or most efficient receiver in a group. A common example is Content Delivery Networks (CDNs), where content is served from the nearest server to the user for faster access.

How does multicasting differ from broadcasting?

Multicasting is one-to-many communication where data is sent from one sender to a group of interested receivers. Broadcasting, on the other hand, sends data to all devices on a network, regardless of interest.

What happens when you type 'www.google.com' into a browser for the first time?

When you type 'www.google.com', the browser first resolves the domain through DNS, then establishes a TCP connection with Google’s server via a 3-way handshake. It initiates a secure TLS/SSL connection, sends an HTTP request, and processes the server’s response to render the webpage. This sequence of events ensures that the page loads securely and efficiently.