100 CompTIA Network+ Terms You Need to Know Before Exam Day

Watch: Network+ 100 Terms

Build your vocabulary before diving into practice questions. This video covers the most important terms — explained clearly, no fluff.

Networking Fundamentals

1. Network — A group of interconnected devices that share resources and communicate. The foundation of all IT infrastructure.

2. OSI Model — The seven-layer framework (Physical, Data Link, Network, Transport, Session, Presentation, Application) for understanding how network protocols work.

3. TCP/IP Model — The practical four-layer model (Network Access, Internet, Transport, Application) that the internet actually runs on.

4. Protocol — A set of rules governing how data is transmitted and received. TCP, UDP, IP, HTTP, and DNS are all protocols.

5. Bandwidth — The maximum data transfer rate of a connection. Measured in bits per second (bps, Mbps, Gbps).

6. Latency — The time delay between sending and receiving data. Measured in milliseconds; critical for real-time applications.

7. Throughput — The actual data transfer rate achieved in practice. Always less than theoretical bandwidth due to overhead and congestion.

8. Topology — The physical or logical arrangement of network devices. Star, bus, ring, mesh, and hybrid topologies.

9. LAN (Local Area Network) — A network connecting devices within a limited geographic area. A home network, office floor, or building.

10. WAN (Wide Area Network) — A network spanning large geographic areas. The internet is the world’s largest WAN.

11. Packet — A unit of data transmitted across a network. Contains headers with addressing and control information plus a payload.

12. Frame — A packet at the data link layer including MAC addresses and error-checking information. The physical layer transmission unit.

13. PDU (Protocol Data Unit) — A unit of information at each OSI layer. Segment at transport, packet at network, frame at data link.

14. Encapsulation — Adding headers and trailers at each OSI layer as data moves down the stack. Each layer wraps the data from the layer above.

15. De-encapsulation — Removing headers and trailers as data moves up the OSI stack. The receiving end reverses encapsulation.

16. Network Address — The address identifying a network. Derived from an IP address and subnet mask.

17. Broadcast Address — The address for sending data to all devices on a network. The last address in a subnet.

18. Unicast — Sending data to a single destination. The most common communication type.

19. Broadcast — Sending data to all devices on a network. Used for DHCP and ARP.

20. Multicast — Sending data to a group of devices. Used for streaming video and audio.

IP Addressing & Subnetting

21. IPv4 — The fourth version of the Internet Protocol using 32-bit addresses (e.g., 192.168.1.1). Provides about 4.3 billion unique addresses.

22. IPv6 — The sixth version using 128-bit addresses in hexadecimal. Designed to solve IPv4 address exhaustion.

23. IP Address Classes — IPv4 address classifications (Class A, B, C, D, E) defining default network and host portions. Legacy concept being replaced by CIDR.

24. Private IP Ranges — Reserved IPv4 ranges not routable on the internet: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

25. Public IP Address — A globally routable IP address assigned by an ISP. Unique across the internet.

26. Loopback Address — A special address (127.0.0.1 in IPv4) for testing the network stack without sending packets on the network.

27. APIPA (Automatic Private IP Addressing) — The 169.254.x.x range automatically assigned when DHCP is unavailable. A reliable indicator of DHCP failure.

28. Subnet Mask — A 32-bit number defining which portion of an IP address is the network vs. the host. 255.255.255.0 (/24) is the most common.

29. CIDR (Classless Inter-Domain Routing) — A method for allocating IP addresses and routing using slash notation (e.g., /24). More flexible than classful addressing.

30. Subnetting — Dividing a network into smaller subnetworks. Critical Network+ skill for efficient IP address management.

31. VLSM (Variable Length Subnet Masking) — Using different subnet mask lengths in the same network. Allows precise allocation based on actual needs.

32. Supernetting — Combining multiple networks into a single larger network. The opposite of subnetting.

33. NAT (Network Address Translation) — Mapping private IP addresses to one or more public IPs for internet communication. Performed by routers and firewalls.

34. PAT (Port Address Translation) — A form of NAT mapping many private IPs to a single public IP using different port numbers. The most common form.

35. Hex Notation — IPv6 addresses use hexadecimal notation (0-9, A-F). More compact than decimal for 128-bit addresses.

36. Link-Local Address — An IPv6 address automatically assigned to interfaces (fe80::/10). Used for local communication.

37. Multicast Address (IPv6) — IPv6 addresses beginning with ff00::/8 for multicast communication. More efficient than IPv4 multicast.

38. Global Unicast Address — A publicly routable IPv6 address (2000::/3). The IPv6 equivalent of IPv4 public addresses.

39. Dual Stack — Running both IPv4 and IPv6 on the same network. The current transition strategy.

40. IPv6 Tunneling — Encapsulating IPv6 packets in IPv4 for transmission over IPv4-only networks. A transition mechanism.

Network Protocols

41. TCP (Transmission Control Protocol) — A connection-oriented protocol guaranteeing reliable, ordered delivery. Used for web browsing, email, and file transfers.

42. UDP (User Datagram Protocol) — A connectionless protocol prioritizing speed over reliability. Used for DNS, DHCP, VoIP, and streaming.

43. ICMP (Internet Control Message Protocol) — Used for network diagnostics and error reporting. Ping and traceroute use ICMP.

44. ARP (Address Resolution Protocol) — Maps IP addresses to MAC addresses. Essential for local network communication.

45. HTTP (Hypertext Transfer Protocol) — The protocol for transmitting web pages. Port 80, unencrypted.

46. HTTPS (HTTP Secure) — HTTP encrypted with TLS. Port 443. Required for any website handling sensitive data.

47. FTP (File Transfer Protocol) — Protocol for transferring files between systems. Port 21, unencrypted. SFTP and FTPS are secure alternatives.

48. SFTP (SSH File Transfer Protocol) — Secure file transfer using SSH encryption. Port 22.

49. SSH (Secure Shell) — Encrypted protocol for secure remote command-line access. Port 22. Replaces Telnet.

50. Telnet — An unencrypted remote access protocol. Port 23. Never use in production; replaced by SSH.

51. DNS (Domain Name System) — Translates domain names to IP addresses. Port 53. The internet’s phonebook.

52. DHCP (Dynamic Host Configuration Protocol) — Automatically assigns IP configurations to network devices. Ports 67/68 (UDP).

53. SMTP (Simple Mail Transfer Protocol) — Protocol for sending email. Port 25 or 587. Works with IMAP and POP3 for receiving.

54. IMAP (Internet Message Access Protocol) — Protocol for accessing server-stored email. Port 143 (or 993 encrypted). Allows multi-device access.

55. POP3 (Post Office Protocol v3) — Protocol downloading email from server to device. Port 110 (or 995 encrypted).

56. SNMP (Simple Network Management Protocol) — Protocol for monitoring and managing network devices. Ports 161/162. Used by network management platforms.

57. NTP (Network Time Protocol) — Synchronizes clocks across network devices. Port 123. Critical for log correlation.

58. LDAP (Lightweight Directory Access Protocol) — Protocol for accessing directory services like Active Directory. Port 389 (or 636 encrypted).

59. Kerberos — An authentication protocol using tickets instead of passwords. The standard for enterprise authentication.

60. RDP (Remote Desktop Protocol) — Microsoft’s protocol for graphical remote access. Port 3389. A high-value attack target.

Network Devices & Components

61. Router — Forwards packets between networks based on IP addresses. The gateway connecting local networks to other networks.

62. Switch — Connects devices within a LAN using MAC addresses. Faster and more efficient than hubs.

63. Hub — An older network device broadcasting traffic to all ports. Replaced by switches due to inefficiency and security issues.

64. Firewall — Controls network traffic based on security rules. Stateful firewalls track connection state; NGFWs add application awareness.

65. Stateful Firewall — Tracks active connections and allows return traffic. The standard in modern deployments.

66. Next-Generation Firewall (NGFW) — A firewall with application awareness, IPS, and threat intelligence. Deeper inspection than traditional firewalls.

67. Load Balancer — Distributes incoming traffic across multiple servers. Improves performance, availability, and redundancy.

68. Proxy Server — An intermediary server handling requests on behalf of clients. Used for filtering, caching, and anonymizing traffic.

69. Reverse Proxy — A proxy server in front of web servers. Used for load balancing and WAF functionality.

70. Content Delivery Network (CDN) — A network of servers caching content geographically closer to users. Reduces latency.

71. Wireless Access Point (WAP) — Connects wireless devices to a wired network. Managed by a wireless LAN controller in enterprise.

72. Wireless LAN Controller (WLC) — Centrally manages multiple wireless access points. Simplifies configuration and security policy.

73. IDS (Intrusion Detection System) — Monitors for suspicious network activity and alerts. IDS watches and warns.

74. IPS (Intrusion Prevention System) — Like IDS but actively blocks malicious traffic. IPS watches and stops.

75. VPN Concentrator — A dedicated device managing VPN connections for many remote users. Provides secure corporate access.

76. Modem — A device converting analog signals (phone/cable lines) to digital (network). Connects ISP service to your router.

77. Network Interface Card (NIC) — A hardware component enabling network connectivity. Can be wired (Ethernet) or wireless (Wi-Fi).

78. Media Converter — Converts between different network media types. Example: fiber to Ethernet.

79. Patch Panel — A termination point where network cables are connected in data centers. Organizes infrastructure.

80. Network Tap (Test Access Point) — A device allowing traffic monitoring without disrupting network flow. Used for security monitoring.

Routing & Switching

81. Routing — The process of forwarding packets between networks. Routers use routing tables and protocols to determine the best path.

82. Routing Table — A database in a router listing network destinations and the interfaces/next-hops to reach them.

83. Default Route — A routing entry used when no specific route matches (0.0.0.0/0 in IPv4). The fallback path.

84. Static Route — A manually configured route that doesn’t change automatically. Simple but requires manual updates.

85. Dynamic Routing — Routing protocols that automatically update routes based on network changes. OSPF, EIGRP, and BGP are examples.

86. OSPF (Open Shortest Path First) — A link-state routing protocol using the shortest path algorithm. Widely used in enterprise networks.

87. EIGRP (Enhanced Interior Gateway Routing Protocol) — A Cisco proprietary routing protocol combining link-state and distance-vector benefits.

88. BGP (Border Gateway Protocol) — The routing protocol of the internet. Used between autonomous systems (ISPs and large organizations).

89. Convergence — The time it takes for routing protocols to update after a network change. Faster convergence means quicker recovery.

90. VLAN (Virtual LAN) — A logical network segment created within a physical switch. Separates traffic for security and performance.

91. Trunking — Carrying multiple VLAN traffic over a single link. Uses 802.1Q tagging to identify which VLAN each frame belongs to.

92. 802.1Q — The IEEE standard for VLAN tagging. Adds a 4-byte tag to frames identifying the VLAN.

93. STP (Spanning Tree Protocol) — Prevents network loops by blocking redundant paths. Critical for network stability.

94. BPDU (Bridge Protocol Data Unit) — The messages STP uses to detect loops and elect a root bridge.

95. EtherChannel / LACP — Bundling multiple physical links into one logical link. Increases bandwidth and provides redundancy.

96. Port Aggregation — Combining multiple network ports to increase bandwidth. Also called link aggregation.

97. Inter-VLAN Routing — Allowing communication between VLANs through a router or Layer 3 switch. Required for VLAN separation to work.

98. MAC Address Table — A switch’s database of which MAC addresses are on which ports. Switches use this for frame forwarding.

99. MAC Address Learning — The process of switches learning source MAC addresses from frames. Populates the MAC address table.

100. CompTIA Network+ Certification — The vendor-neutral networking certification validating skills in network design, configuration, management, and troubleshooting. Your essential stepping stone to Security+ and a networking career.

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