Networking Core Cheat Sheet

Updated 2026-04-28

Networking forms the foundation of modern computing, enabling devices to communicate and share resources across local and global infrastructures. From the seven-layer OSI model to protocols managing everything from IP addressing to data encryption, networking encompasses both physical transmission media and logical routing decisions. Understanding networking means grasping how packets traverse routers, switches, and firewalls—and how a single misconfigured subnet mask or firewall rule can cascade into widespread connectivity failures or security breaches. In 2026, modern architectures increasingly embrace zero trust, SD-WAN, and SASE, shifting from perimeter-based security toward identity-driven, cloud-delivered models that follow users and applications rather than fixed network boundaries.

What This Cheat Sheet Covers

This topic spans 23 focused tables and 238 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: OSI and TCP/IP Model LayersTable 2: Core Network ProtocolsTable 3: IP Addressing and SubnettingTable 4: DNS Record TypesTable 5: Network DevicesTable 6: Network TopologiesTable 7: Network Types and ClassificationsTable 8: Wireless Networking StandardsTable 9: Ethernet Cable StandardsTable 10: Common Port NumbersTable 11: Routing ProtocolsTable 12: Network Address TranslationTable 13: VLANs and Network SegmentationTable 14: Network Security FundamentalsTable 15: Network Performance MetricsTable 16: Network Troubleshooting ToolsTable 17: Transport Layer ProtocolsTable 18: Quality of Service (QoS)Table 19: Spanning Tree ProtocolTable 20: Load Balancing and RedundancyTable 21: Network Monitoring and ManagementTable 22: Advanced Networking ConceptsTable 23: Traffic Types and Transmission Methods

Table 1: OSI and TCP/IP Model Layers

The OSI model is the mental scaffold every network engineer reaches for when something breaks—peel the stack from the application down to the physical wire and you can pin a problem to a single layer. These rows line up the seven OSI layers against the four practical TCP/IP layers that actually run the internet, so you can see where a protocol lives and which layer collapses into which.

Layer	Example	Description
Application Layer (Layer 7)	HTTP, FTP, DNS, SSH	• Provides network services directly to user applications • handles protocols for web browsing, file transfer, and email.
Presentation Layer (Layer 6)	SSL/TLS, JPEG, ASCII	Translates data formats, handles encryption/decryption, and manages compression for the application layer.
Session Layer (Layer 5)	NetBIOS, RPC	• Establishes, manages, and terminates sessions between applications • controls dialog and synchronization.
Transport Layer (Layer 4)	TCP, UDP	• Provides end-to-end communication, flow control, and error recovery • segments data and manages port numbers.
Network Layer (Layer 3)	IP, ICMP, OSPF, BGP	• Handles logical addressing (IP) and routing • determines best path for packets across networks.
Data Link Layer (Layer 2)	Ethernet, Wi-Fi (802.11), PPP	• Manages MAC addressing and frame transmission • handles error detection and media access control.

Table 1: OSI and TCP/IP Model Layers

Layer	Example	Description
Application Layer (Layer 7)	HTTP, FTP, DNS, SSH	• Provides network services directly to user applications • handles protocols for web browsing, file transfer, and email.
Presentation Layer (Layer 6)	SSL/TLS, JPEG, ASCII	Translates data formats, handles encryption/decryption, and manages compression for the application layer.
Session Layer (Layer 5)	NetBIOS, RPC	• Establishes, manages, and terminates sessions between applications • controls dialog and synchronization.
Transport Layer (Layer 4)	TCP, UDP	• Provides end-to-end communication, flow control, and error recovery • segments data and manages port numbers.
Network Layer (Layer 3)	IP, ICMP, OSPF, BGP	• Handles logical addressing (IP) and routing • determines best path for packets across networks.
Data Link Layer (Layer 2)	Ethernet, Wi-Fi (802.11), PPP	• Manages MAC addressing and frame transmission • handles error detection and media access control.