Fundamentals of Computer Networking: Key Concepts and Definitions

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

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

3. What is a backbone network? A backbone network is a centralized infrastructure that routes and distributes data across various networks, handling bandwidth management and multiple channels.

4. What is a LAN? LAN stands for Local Area Network, describing connections between computers and other network devices within a small physical area.

5. What is a node? A node is a point where a connection occurs, such as a computer or device that is part of a network; at least two nodes are required to form a network link.

6. What is a router? A router connects two or more network segments, storing routing information (paths, hop counts, etc.) in its routing table to determine optimal data paths, and operates 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 machines without additional networking equipment.

8. What is anonymous FTP? Anonymous FTP allows users to access files on a public server without identifying themselves, logging in 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 the address; it is also 32 bits long.

10. What is data encapsulation? Data encapsulation is the process of breaking information into smaller, manageable units before transmission, adding source and destination addresses and error‑checking information to headers.

11. What is a VPN? VPN (Virtual Private Network) creates a secure tunnel over a network such as the Internet, allowing safe remote connections to servers.

12. What is NAT? NAT (Network Address Translation) is a protocol that enables multiple computers on a private network to share a single public Internet connection.

13. What is the function of the Network layer in the OSI model? The Network layer handles data routing, packet switching, and network congestion control; routers operate at this layer.

14. What is RIP? RIP (Routing Information Protocol) is used by routers to send data from one network to another, broadcasting routing tables to all routers and measuring distance in hops.

15. What is a WAN? WAN (Wide Area Network) interconnects geographically dispersed computers and devices, linking networks across different regions and countries.

16. Why is the OSI Physical layer important? The Physical layer converts data bits to electrical signals (and vice versa) and concerns the selection and configuration of network devices and cabling.

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

18. What are proxy servers and how do they protect networks? Proxy servers hide internal network IP addresses from external users, making it difficult to identify or locate the network, thereby providing a layer of protection.

19. 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.

20. What does 10Base‑T mean? "10" denotes a 10 Mbps data rate, "Base" indicates baseband signaling, and "T" refers to twisted‑pair cabling.

21. What is a private IP address? Private IP addresses are assigned for internal networks, are not routable on the public Internet, and can be reused across multiple isolated networks.

22. What is a DoS attack? A Denial‑of‑Service (DoS) attack attempts to prevent users from accessing network services by overwhelming a system with traffic.

23. 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.

24. What is the main purpose of OSPF? OSPF (Open Shortest Path First) is a link‑state routing protocol that determines optimal data paths using routing tables.

25. What is a firewall? A firewall protects an internal network from external attacks, blocking unauthorized access and malicious traffic.

26. What is a gateway? A gateway connects two or more network segments, typically running gateway software to translate between different network protocols.

27. Examples of private network address ranges. 10.0.0.0/8 (subnet mask 255.0.0.0), 172.16.0.0/12 (subnet mask 255.240.0.0), and 192.168.0.0/16.

28. What is tracert? Tracert is a Windows utility that traces the route packets take from a router to a destination network, showing hop counts.

29. What is DHCP? DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices on a network by allocating the next available address.

30. What is the primary function of ARP? ARP (Address Resolution Protocol) maps known IP addresses to their corresponding MAC (layer‑2) addresses.

31. What is TCP/IP? TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of protocols that enables data exchange across heterogeneous computer networks.

32. What is ICMP? ICMP (Internet Control Message Protocol) provides messaging and error reporting for the TCP/IP protocol suite, used by tools like ping.

33. What are the advantages of fiber optic cables over other media? Fiber optics are less susceptible to electrical interference, support higher bandwidth, and experience minimal signal degradation over long distances.

34. Which network protocols are supported by Windows RRAS? Windows RRAS supports three primary network protocols: NetBEUI, TCP/IP, and IPX.

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

36. Which protocols reside below the application layer in the TCP/IP stack? Application‑layer protocols include FTP, TFTP, Telnet, and SMTP.

37. Describe Ethernet. Ethernet is a widely used networking technology developed in the early 1970s, based on IEEE standards, and commonly employed in LANs.

38. What is SMTP? SMTP (Simple Mail Transfer Protocol) handles the transmission of email messages within the TCP/IP suite.

39. What is multicast routing? Multicast routing sends messages to a selected group of users rather than broadcasting to all users on a subnet.

40. What does tunnel mode mean? Tunnel mode creates a virtual tunnel using IPSec to protect all traffic between a LAN and a transit network, without the communicating computers using IPSec directly.

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

42. What is IPv6? IPv6 (Internet Protocol version 6) was developed to replace IPv4, addressing IPv4 address exhaustion and providing a larger address space.

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

44. What is the maximum segment length for a 100Base‑FX network? The maximum allowed segment length for 100Base‑FX is 412 meters, with a total network length of up to 5 kilometers.