Essential Networking Q&A: 100 Key Concepts Explained

1) What is a link? A link refers to the connection between two devices, including the cable type and protocol that enable communication.

2) What are the OSI reference model layers? There are seven OSI layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

3) What is a backbone network? A backbone network is a centralized infrastructure designed to route and distribute data across various networks, handling bandwidth management and multiple channels.

4) What is a LAN? LAN stands for Local Area Network, which connects computers and other network devices within a small physical area.

5) What is a node? A node is a point where a connection occurs; it can be a computer or device that is part of a network, requiring at least two nodes to form a network connection.

6) What is a router? A router connects two or more network segments and stores routing information such as paths and hop counts, operating at the OSI network layer.

7) What is a point‑to‑point link? It is a direct connection between two computers on a network, requiring only a cable between the NICs without additional networking devices.

8) What is anonymous FTP? Anonymous FTP allows users to access public server files without identifying themselves, logging in as an anonymous guest.

9) What is a subnet mask? A subnet mask works with an IP address to identify the network and host portions; like an IP address, it consists of 32 bits.

10) What is the maximum length allowed for a UTP cable segment? A single UTP cable segment may be 90 to 100 meters long; repeaters or switches can extend this limit.

11) What is data encapsulation? Data encapsulation is the process of breaking information into smaller, manageable blocks before transmission, adding source and destination addresses and parity to the header.

12) Describe network topology. Network topology refers to the physical layout of a computer network, showing how devices and cables are arranged and interconnected.

13) What is a VPN? VPN (Virtual Private Network) creates a secure tunnel over a network such as the Internet.

14) What is NAT? NAT (Network Address Translation) allows multiple computers on a public network to share a single Internet connection.

15) What does the network layer do in the OSI model? The network layer handles data routing, packet switching, and network congestion control; routers operate at this layer.

16) How does network topology affect decisions when building a network? Topology determines the media required for interconnecting devices and influences the choice of cables, connectors, and terminals.

17) What is RIP? RIP (Routing Information Protocol) is used by routers to send data between networks, broadcasting routing tables and measuring distance in hops.

18) How can a computer network be protected? Protection methods include installing reliable antivirus software, correctly configuring firewalls, and using user authentication.

19) What is a NIC? NIC stands for Network Interface Card, a hardware component that connects a PC to a network and has a unique MAC address.

20) What is a WAN? WAN (Wide Area Network) interconnects geographically dispersed computers and devices across different regions or countries.

21) Why is the OSI physical layer important? The physical layer converts data bits to electrical signals and vice versa, influencing device and cable selection.

22) How many layers are there in TCP/IP? TCP/IP has four layers: Network, Internet, Transport, and Application.

23) What is a proxy server and how does it protect a network? A proxy server hides internal IP addresses from external users, making the network difficult to locate and access.

24) What is the function of the OSI session layer? The session layer provides protocols and methods for two devices to establish, manage, and terminate communication sessions.

25) Why implement fault‑tolerant systems? Fault‑tolerant systems ensure continuous data availability by eliminating single points of failure, though they cannot protect against accidental deletions.

26) What does 10Base‑T mean? "10" indicates a 10 Mbps data rate, "Base" denotes baseband, and "T" stands for twisted‑pair cable.

27) What are private IP addresses? Private IP addresses are assigned for internal networks and are not routable on the public Internet, preventing address conflicts.

28) What is NOS? NOS (Network Operating System) is software that provides network connectivity for computers to communicate with other devices.

29) What is a DoS? DoS (Denial‑of‑Service) attacks attempt to prevent users from accessing network services by overwhelming the target system.

30) What is OSI and its role in computer networking? OSI (Open Systems Interconnection) is a reference model with seven layers that define how network devices communicate.

31) Why are cables shielded and twisted‑pair? Shielding and twisting reduce crosstalk and electromagnetic interference, preserving signal integrity.

32) What are the advantages of address sharing? Using address translation provides inherent security because external hosts see only the public IP of the NAT device.

33) What is a MAC address? MAC (Media Access Control) uniquely identifies a device on a network; it consists of six bytes.

34) Which TCP/IP protocols correspond to the OSI application layer? FTP, TFTP, Telnet, and SMTP map to the OSI application layer.

35) How can you identify the class of an IP address? Examine the first octet: 0‑127 for Class A, 128‑191 for Class B, 192‑223 for Class C.

36) What is the primary purpose of OSPF? OSPF (Open Shortest Path First) is a link‑state routing protocol that determines the best path using routing tables.

37) What is a firewall? A firewall protects an internal network from external attacks such as hackers or viruses and blocks unauthorized access.

38) Describe star topology. Star topology connects all nodes to a central hub, making it simple to set up and maintain.

39) What is a gateway? A gateway connects two or more network segments and performs protocol translation to enable communication.

40) What is a drawback of star topology? If the central hub or switch fails, the entire network becomes unavailable.

41) What is SLIP? SLIP (Serial Line Internet Protocol) is an older protocol used for remote access on early UNIX systems.

42) Give examples of private network addresses. 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

43) What is netstat? Netstat is a command‑line utility that provides information about current TCP/IP connections.

44) What is the role of a network administrator? Network administrators install, configure, and maintain networks, handling troubleshooting as needed.

45) What is a disadvantage of a peer‑to‑peer network? Accessing resources from a shared workstation can degrade its performance.

46) What is a hybrid network? A hybrid network combines client‑server and peer‑to‑peer architectures.

47) What is DHCP? DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices on a network.

48) What is the main function of ARP? ARP (Address Resolution Protocol) maps known IP addresses to MAC addresses.

49) What is TCP/IP? TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of protocols for data exchange across heterogeneous networks.

50) How can a router manage a network? Routers provide consoles to configure security, data logging, access restrictions, and time‑based policies.

51) Which protocol can be used to transfer files between UNIX and Windows servers? FTP (File Transfer Protocol) is platform‑independent and suitable for such transfers.

52) What is the purpose of a default gateway? It provides a path for a local network to reach external networks, typically using the router’s external interface.

53) What makes a good password? A strong password combines letters, numbers, and mixed case, avoiding easily guessed information.

54) What is the correct termination resistance for a UTP cable? The normal termination resistance for unshielded twisted‑pair cable is 100 Ω.

55) What is ICMP? ICMP (Internet Control Message Protocol) provides messaging and error handling for the TCP/IP stack.

56) How many network IDs are available in a Class C network? A Class C network has 21 bits for network ID, yielding 2,097,152 possible networks, each with up to 254 hosts.

57) What happens if a cable exceeds its specified length? Signal loss occurs, degrading data transmission and reception.

58) What common software problems can cause network defects? Issues include client‑server conflicts, application clashes, misconfiguration, protocol mismatches, security problems, and policy violations.

59) What is ICMP? ICMP (Internet Control Message Protocol) provides messages for error handling and diagnostics within the TCP/IP suite.

60) What is Ping? Ping is a utility that checks connectivity between network devices using their IP address or hostname.

61) What is P2P? Peer‑to‑peer networks consist of equal workstations that communicate directly without a central server.

62) What is DNS? DNS (Domain Name System) resolves hostnames to TCP/IP addresses.

63) What advantage does fiber have over other media? Fiber is less susceptible to electrical interference, supports higher bandwidth, and experiences minimal signal degradation over long distances.

64) What is the difference between a hub and a switch? A hub acts as a multi‑port repeater and cannot efficiently manage traffic as more devices connect, whereas a switch improves performance by directing traffic to specific ports.

65) Which network protocols does Windows RRAS support? NetBEUI, TCP/IP, and IPX.

66) What are the maximum networks and hosts for Class A, B, and C? Class A: 126 networks, 16,777,214 hosts; Class B: 16,384 networks, 65,534 hosts; Class C: 2,097,152 networks, 254 hosts.

67) What is the standard color order for a straight‑through cable? Orange/white, orange, green/white, blue, blue/white, green, brown/white, brown.

68) Which protocol lies below the TCP/IP application layer? FTP, TFTP, Telnet, and SMTP are application‑layer protocols.

69) Can two computers share files without a hub or router? Yes, by using a crossover cable that swaps transmit and receive pins.

70) What is ipconfig? ipconfig is a utility that displays a computer’s IP configuration, including physical and IP addresses.

71) What is the difference between straight‑through and crossover cables? Straight‑through cables connect devices to hubs, switches, or routers; crossover cables connect similar devices directly (e.g., PC‑to‑PC).

72) What is client/server? In a client/server network, one or more servers provide centralized resources such as printers and files, while clients access these resources.

73) Describe a network. A network is the interconnection of computers and peripheral devices for data communication, using wired cables or wireless links.

74) Does moving a NIC card transfer its MAC address? Yes, the MAC address is hard‑wired to the NIC hardware, not the PC.

75) Explain clustering support. Clustering allows multiple servers to operate together so that if one fails, another continues processing.

76) Where should antivirus be installed in a network with two servers and twenty workstations? Antivirus should be installed on all servers and workstations to protect against virus introduction via removable media.

77) Describe Ethernet. Ethernet is a widely used network technology developed in the early 1970s, based on IEEE standards, primarily used in LANs.

78) What is a drawback of ring topology? A single workstation failure can bring down the entire network, and reconfiguration may require temporary shutdown.

79) What is the difference between CSMA/CD and CSMA/CA? CSMA/CD (Collision Detection) retransmits after a collision; CSMA/CA (Collision Avoidance) broadcasts intent before transmitting.

80) What is SMTP? SMTP (Simple Mail Transfer Protocol) handles internal mail delivery over the TCP/IP stack.

81) What is multicast routing? Multicast routing sends messages to a selected group of users rather than broadcasting to an entire subnet.

82) Why is encryption important on a network? Encryption converts information into unreadable code, ensuring intercepted data remains unintelligible without the correct key.

83) How are IP addresses formatted? IP addresses are displayed as four decimal numbers separated by periods (dot‑decimal notation), e.g., 192.168.101.2.

84) Explain the importance of authentication. Authentication verifies user credentials before granting network access, typically using usernames and passwords to prevent unauthorized entry.

85) What does tunnel mode mean? Tunnel mode creates a virtual IPSec tunnel that secures all communication between a LAN and a gateway.

86) What technologies are involved in establishing a WAN link? Analog connections (regular telephone lines), digital connections (digital telephone lines), and switched connections (multiple link sets).

87) What is an advantage of mesh topology? Mesh topology provides redundancy; if one link fails, another is available, making it highly fault‑tolerant.

88) What common hardware issues can arise when troubleshooting a network? Issues may include hard‑drive failures, damaged NICs, hardware startup problems, or incorrect hardware configuration.

89) How can signal attenuation be fixed? Use repeaters or hubs to regenerate the signal and ensure proper cable termination.

90) How does DHCP assist network management? DHCP allows administrators to assign IP addresses dynamically from a pool, eliminating the need to configure static addresses on each client.

91) What is a network permission? A permission authorizes a user to perform specific actions on the network, varying per user.

92) What is a VLAN? A VLAN creates separate broadcast domains at the switch level, enhancing security and traffic segmentation.

93) What is IPv6? IPv6 (Internet Protocol version 6) was developed to replace IPv4, addressing the exhaustion of IPv4 addresses.

94) What is the RSA algorithm? RSA (Rivest‑Shamir‑Adleman) is the most widely used public‑key encryption algorithm.

95) What is a mesh topology? Mesh topology connects each device directly to every other device, requiring at least two connections per device.

96) What is the maximum segment length for 100Base‑FX? A 100Base‑FX segment can be up to 412 meters; the total network length can reach up to 5 kilometers.