Top 100 Networking Fundamentals: Key Concepts and FAQs Explained

1) What is a link? A link refers to the connection between two devices, including the cable type and protocol that allow one device to communicate with another.

2) What are the layers of the OSI reference model? 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 that distributes routing and 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. Two or more nodes are required to form a network connection.

6) What is a router? A router can connect two or more network segments. It stores routing information such as paths and hop counts in its routing table, allowing it to determine the optimal path for data transmission. Routers operate 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 connecting the NICs of the two computers without any additional network devices.

8) What is anonymous FTP? Anonymous FTP grants users access to files on a public server without requiring identification, allowing login as an anonymous guest.

9) What is a subnet mask? A subnet mask, combined with an IP address, identifies the network portion and the host portion of an address. Like an IP address, a subnet mask consists of 32 bits.

10) What is the maximum length allowed for a UTP cable? A single segment of UTP cable may be 90 to 100 meters long; this limitation can be overcome using repeaters and switches.

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

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

13) What is a VPN? VPN stands for Virtual Private Network, a technology that creates a secure tunnel over a network such as the Internet.

For example, a VPN allows you to establish a secure dial‑up connection to a remote server.

14) What is NAT? NAT (Network Address Translation) is a protocol that enables 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 is responsible for 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 that interconnecting devices must use and serves as the basis for selecting cables, connectors, and terminals.

17) What is RIP? RIP (Routing Information Protocol) is used by routers to send data from one network to another. It broadcasts its routing table to all other routers, using hop count to determine network distance.

18) What are different ways to protect a computer network? Install reliable, up‑to‑date antivirus on all computers, ensure firewalls are properly configured, and use strong user authentication. These measures together create a highly secure network.

19) What is a NIC? NIC stands for Network Interface Card. It connects a PC to network devices, and each NIC has its own MAC address for identification on the network.

20) What is a WAN? WAN stands for Wide Area Network, interconnecting 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, involving considerations of network devices and cable types.

22) How many layers are there in TCP/IP? There are 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 network IP addresses from external users, making the network’s physical location difficult to discover and preventing outsiders from seeing internal resources.

24) What is the function of the OSI Session layer? The Session layer provides protocols and methods for two devices on a network to communicate, including establishing, managing, and terminating sessions.

25) Why is implementing a fault‑tolerant system important? Are there limits? Fault‑tolerant systems ensure continuous data availability by eliminating single points of failure, though they cannot protect against all issues such as accidental deletion.

26) What does 10Base‑T mean? "10" indicates a data rate of 10 Mbps, "Base" refers to baseband, and "T" denotes twisted‑pair cable used for the network.

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

28) What is a NOS? NOS (Network Operating System) is software that provides network connectivity for computers, enabling communication with other computers and devices.

29) What is a DoS? A DoS (Denial of Service) attack attempts to prevent users from accessing Internet or network services, often by overwhelming a server with traffic.

30) What is OSI and what role does it play in computer networking? OSI (Open Systems Interconnection) is a reference model for data communication consisting of seven layers, each defining how network devices interact and transmit data.

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

32) What are the advantages of address sharing? Using address translation instead of routing provides inherent security because external hosts see only the public IP of the translating device, not internal private addresses.

33) What is a MAC address? A MAC (Media Access Control) address uniquely identifies a device on a network; it is a 6‑byte physical address.

34) Which TCP/IP protocols correspond to the OSI Application layer? The TCP/IP Application layer maps to three OSI layers: Session, Presentation, and Application.

35) How can you identify the class of a given IP address? By examining the first octet: values starting with 0 indicate Class A, 10 indicate Class B, and 110 indicate Class C.

36) What is the main purpose of OSPF? OSPF (Open Shortest Path First) is a link‑state routing protocol that uses routing tables to determine the best path for data exchange.

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

38) Describe star topology. Star topology consists of a central hub to which all nodes are connected, making it simple to set up and maintain.

39) What is a gateway? A gateway provides connectivity between two or more network segments, typically running software that translates protocols 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 developed for early UNIX systems to provide remote access.

42) Give examples of private network addresses. 10.0.0.0/8 (subnet mask 255.0.0.0) and 172.16.0.0/12 (subnet mask 255.240.0.0).

43) What is tracert? Tracert is a Windows utility that traces the route packets take from a router to a destination network, showing the number of hops.

44) What are the roles of a network administrator? Installing networks, configuring network settings, and maintaining/troubleshooting the network.

45) Describe a drawback of a peer‑to‑peer network. When a workstation shares resources, its performance may degrade.

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 from an available pool.

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 that enable data exchange across heterogeneous computer networks.

50) How can a router be used to manage a network? Routers have consoles for configuring settings such as security, data logging, access restrictions, and time‑based internet usage.

51) Which protocol is used to transfer files between UNIX systems and Windows servers? FTP (File Transfer Protocol) enables platform‑independent file transfer.

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

53) What makes a good password? A strong password combines letters (both uppercase and lowercase) and numbers, avoiding easily guessable information such as dates or names.

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

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

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 network IDs; each network can have 254 host IDs.

57) What happens when a cable exceeds the specified length? Excessive length causes signal loss, degrading data transmission and reception.

58) What common software issues can cause network defects? Client‑server problems, application conflicts, configuration errors, protocol mismatches, security issues, and user policy violations.

59) What is ICMP? ICMP (Internet Control Message Protocol) provides messaging and communication within the TCP/IP stack and manages error messages used by tools like ping.

60) What is Ping? Ping is a utility that checks connectivity between network devices by sending ICMP echo requests.

61) What is P2P? Peer‑to‑peer (P2P) 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 are the advantages of fiber 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, while a switch intelligently forwards traffic, improving performance especially under high load.

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

66) What are the maximum numbers of 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 protocols lie below the TCP/IP Application layer? FTP, TFTP, Telnet, and SMTP.

69) Can two computers share files without a hub or router? Yes, by using a crossover cable that connects the transmit pins of one computer to the receive pins of the other.

70) What is ipconfig? ipconfig is a utility that displays a computer’s network address information, including physical (MAC) and IP addresses.

71) What is the difference between straight‑through and crossover cables? Straight‑through cables connect a computer to a hub, switch, or router; crossover cables connect similar devices directly, such as PC‑to‑PC.

72) What is client/server? In a client/server network, one or more computers act as servers providing centralized resources (e.g., printers, files) to client workstations.

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 to another PC move its MAC address? Yes, because the MAC address is hard‑wired to the NIC circuitry, not the PC.

75) What is cluster support? Cluster support allows a network operating system to connect multiple servers in a fault‑tolerant group, ensuring continuity if one server fails.

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, and commonly used in LANs.

78) What are the disadvantages of a ring topology? A single workstation failure can bring down the entire network, and reconfiguring a portion of the network may require temporary shutdown.

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

80) What is SMTP? SMTP (Simple Mail Transfer Protocol) handles internal mail and provides mail delivery services on 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 transforms information into unreadable code, ensuring that intercepted data remains unintelligible without the correct key or password.

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) Why is authentication important? Authentication verifies user credentials before allowing network access, limiting harmful intruders.

85) What does tunnel mode mean? Tunnel mode creates a virtual tunnel using IPSec to protect all communications between two LANs via a gateway, without the communicating computers using IPSec directly.

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

87) What is an advantage of mesh topology? If one link fails, another link is available, making mesh topology highly fault‑tolerant.

88) What common hardware issues can arise when troubleshooting network problems? Hard‑disk failures, damaged NICs, hardware startup problems, and incorrect hardware configuration.

89) How can signal attenuation problems be fixed? Use repeaters or hubs to regenerate the signal and ensure cables are properly terminated.

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

91) Explain the concept of a network profile. A network profile is a set of configuration settings applied to a user, such as grouping users into a specific profile.

92) What is Sneakernet? Sneakernet is an early form of networking that physically transports data using removable media like disks or tapes.

93) What is the role of IEEE in computer networking? IEEE (Institute of Electrical and Electronics Engineers) develops and manages standards for network equipment, interfaces, cabling, and connectors.

94) Which protocols are under the TCP/IP Internet layer? ICMP, IGMP, IP, and ARP.

95) What does permission mean in a network context? Permission is an authorized right for a user to perform specific actions on the network.

96) What is a basic requirement for creating a VLAN? A VLAN creates a separate broadcast domain at the switch level, improving security and segmenting traffic.

97) What is IPv6? IPv6 (Internet Protocol version 6) was developed to replace IPv4, which is exhausted, providing a vastly larger address space.

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

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

100) What is the maximum segment length for a 100Base‑FX network? The maximum allowed segment length is 412 meters; the overall network can extend up to 5 kilometers.