Networking Interview Questions and Answers

This section covers a range of networking interview questions, focusing on network topologies, distributed processing, network reliability, and key networking concepts.

What is a Network?

A network is a collection of interconnected devices (computers, servers, etc.) that can share data and resources. The connections can be physical (cables) or wireless. The internet is a massive example of a global network.

Network Topologies

Network topology describes the physical or logical layout of a network:

• Bus: All devices connect to a single cable. Simple but a failure in the cable brings down the whole network.
• Star: All devices connect to a central hub or switch. More robust as a single cable failure only affects one device.
• Ring: Devices connect in a circular fashion. A failure in a single connection point can disrupt the whole network.
• Mesh: Devices have multiple connections to other devices. Robust but complex and expensive.
• Tree: Combines star and bus topologies; failures in a segment only affect that segment.
• Hybrid: A combination of different topologies.

Advantages of Distributed Processing

• Enhanced security (redundancy).
• Improved modularity and maintainability (encapsulation).
• Support for distributed databases.
• Faster problem-solving (parallel processing).
• Increased collaboration.

Network Reliability

Network reliability measures a network's ability to function as intended. Key factors affecting reliability include:

• Downtime: Time the network is unavailable.
• Failure frequency: How often the network fails.
• Catastrophic failures: Major disruptions (e.g., natural disasters).

Factors Affecting Network Security

• Unauthorized access
• Malicious software (viruses, malware)

Factors Affecting Network Reliability

• Frequency of failures
• Recovery time after failures

Factors Affecting Network Performance

• Number of users
• Type of transmission medium
• Hardware capabilities
• Software efficiency

Criteria for Effective and Efficient Networks

• Performance: Transmission speed, response time.
• Reliability: Minimizing downtime and failures.
• Robustness: Ability to withstand failures.
• Security: Protection against threats.

Bandwidth

Bandwidth is the range of frequencies available for data transmission. A wider bandwidth allows for higher data transfer rates.

Nodes and Links

In a network, a node is a device (like a computer), and a link is the physical or wireless connection between nodes.

Gateways and Routers

A gateway connects dissimilar networks. A router connects similar networks. Both forward data packets between networks.

DNS (Domain Name System)

DNS translates domain names (like example.com) into IP addresses (like 192.168.1.1), making it easier for users to access resources on the internet.

DNS Forwarders

DNS forwarders act as intermediaries, forwarding DNS queries they can't resolve to other DNS servers. This improves performance and reduces the load on internal DNS servers.

NIC (Network Interface Card)

A NIC is a device that allows a computer to connect to a network. Each NIC has a unique MAC address.

10Base-T

10Base-T specifies a network with a 10 Mbps data transfer rate using baseband signaling over twisted-pair cabling.

NOS (Network Operating System)

A NOS is software that manages and controls a computer network, allowing devices to communicate and share resources.

Types of Networks (Based on Geographical Area)

• PAN (Personal Area Network): Small range (around 10 meters).
• LAN (Local Area Network): Small geographical area (e.g., office, home).
• HAN (Home Area Network): A LAN within a home.
• CAN (Campus Area Network): Connects multiple LANs within a campus.
• MAN (Metropolitan Area Network): Larger geographical area (e.g., a city).
• WAN (Wide Area Network): Connects networks over a large geographical area (e.g., the internet).

Infrared (IR) Transmission

IR uses infrared light waves for short-range wireless communication. It's commonly used for remote controls and short-range data transfers.

Applications of Infrared in Mobile Communication

• Remote controls
• Wireless peripherals
• Short-range data transfer

Network Topologies

Network topology refers to the physical or logical layout of a network. Common topologies include:

• Bus: All devices connect to a single cable. Simple but vulnerable to single points of failure.
• Star: Devices connect to a central hub or switch. More reliable than a bus topology.
• Ring: Devices form a closed loop. A single point of failure can disrupt the entire network.
• Mesh: Devices have multiple connections. Highly reliable but complex and expensive.
• Tree: Combines star and bus topologies. Failures are typically isolated to segments.
• Hybrid: A combination of multiple topologies.

Advantages of Distributed Processing

Distributed processing distributes tasks across multiple computers, improving:

• Security (redundancy).
• Maintainability (modularity).
• Scalability (handling larger workloads).
• Performance (parallel processing).

Network Reliability Metrics

Network reliability is measured by:

• Downtime: Time the network is unavailable.
• Mean Time Between Failures (MTBF): Average time between failures.
• Mean Time To Repair (MTTR): Average time to restore service after a failure.

Factors Affecting Network Security

• Unauthorized access.
• Malware (viruses, worms).
• Vulnerable configurations.

Factors Affecting Network Performance

• Number of users
• Network congestion
• Transmission speed
• Hardware capabilities
• Software efficiency

Key Aspects of Effective Networks

• High performance
• High reliability
• Robustness
• Strong security

Bandwidth

Bandwidth is the range of frequencies a communication medium can carry. A larger bandwidth generally means faster data transfer rates.

Nodes and Links

A node is a device on a network (computer, printer, etc.). A link is the communication path between nodes.

Gateways and Routers

Both forward data packets. A router operates within the same type of network. A gateway connects different network types.

DNS (Domain Name System)

DNS translates domain names (like example.com) to IP addresses (like 192.168.1.100), making it easier for users to access network resources.

DNS Forwarders

A DNS forwarder forwards DNS queries it cannot resolve internally to external DNS servers.

NIC (Network Interface Card)

A NIC is a hardware component that allows a device to connect to a network.

10Base-T

10Base-T refers to a network standard with a 10 Mbps data rate using baseband signaling over twisted-pair cable.

NOS (Network Operating System)

A NOS is specialized software that manages and controls a network.

Types of Networks

Networks are classified based on their geographical coverage:

• PAN (Personal Area Network): Small area (e.g., a person's desk).
• LAN (Local Area Network): Small area (e.g., office, home).
• HAN (Home Area Network): LAN within a home.
• CAN (Campus Area Network): Multiple LANs within a campus.
• MAN (Metropolitan Area Network): A city or region.
• WAN (Wide Area Network): Large geographical area (e.g., the internet).
• GAN (Global Area Network): Global network (using satellites).

POP3 (Post Office Protocol version 3)

POP3 is a protocol used to retrieve emails from a mail server to a client machine. It operates in delete or keep modes.

MAC Address (Media Access Control Address)

A MAC address is a unique hardware identifier for network interfaces.

IP Address (Internet Protocol Address)

An IP address is a numerical label assigned to devices connected to a computer network. It enables communication between devices.

Private IP Addresses

Private IP addresses are reserved for internal networks and are not routable on the public internet.

Public IP Addresses

Public IP addresses are assigned to devices that are accessible via the public internet.

APIPA (Automatic Private IP Addressing)

APIPA is a feature in Windows that automatically assigns IP addresses to computers on a local network if a DHCP server is unavailable.

ADS (Active Directory Structure)

Active Directory is Microsoft's directory service for managing network resources (users, computers, groups, etc.). It's hierarchical (domain, tree, forest).

RAID (Redundant Array of Independent Disks)

RAID is a technology that uses multiple hard disk drives to increase storage capacity and provide fault tolerance (data protection against hard drive failures).

Anonymous FTP

Anonymous FTP allows accessing files on a server without authentication (using a guest account).

Network Protocols

A protocol defines rules governing data communication. Key elements include syntax, semantics, and timing.

Domain Name System (DNS)

DNS translates domain names (like example.com) to IP addresses.

Network Links

Links are the physical (cables) or wireless connections between network devices.

OSI (Open Systems Interconnection) Reference Model

The OSI model is a conceptual framework for understanding network communication. It consists of seven layers.

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

OSI Physical Layer

The physical layer deals with the physical transmission of data (cables, signals).

OSI Session Layer

The session layer establishes, manages, and terminates communication sessions between applications.

UTP Cable Length

Unshielded Twisted Pair (UTP) cables typically have a maximum length of around 100 meters.

RIP (Routing Information Protocol)

RIP is a dynamic routing protocol that uses a hop count algorithm to determine the best path for data packets.

TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP is a suite of protocols that forms the basis of the internet.

netstat Command

The netstat command displays network connection information.

ping Command

The ping command tests network connectivity by sending ICMP echo requests.

Sneakernet

Sneakernet refers to transferring data physically (using removable media).

Peer-to-Peer Processes

Peer-to-peer processes are processes on different computers that communicate directly at the same layer of the network model.

Congested Switch

A congested switch receives packets faster than it can forward them, causing packet loss.

Multiplexing

Multiplexing allows multiple signals to share a single communication channel.

Advantages of Address Sharing (NAT)

Network Address Translation (NAT) provides a security benefit by hiding internal IP addresses from the public internet. External systems only see the public IP address of the NAT device.

RSA Algorithm

RSA (Rivest-Shamir-Adleman) is a widely used public-key cryptosystem for secure data transmission. It's an asymmetric encryption algorithm, meaning it uses separate keys for encryption and decryption.

Layers in the TCP/IP Model

The TCP/IP model has four layers:

1. Application Layer
2. Transport Layer
3. Internet Layer
4. Network Access Layer

TCP/IP vs. OSI Model

Workgroups vs. Domains