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Networking & Security Glossary
An ongoing encyclopedia of essential network engineering protocols, acronyms, and operational theories. Click any term or tag for a deep-dive analysis.
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A - E
| Term / Acronym | Tags | Definition Summary |
|---|---|---|
| 802.1Q | The IEEE standard for VLAN tagging. It inserts a 4-byte field into the Ethernet header to identify which VLAN a frame belongs to as it crosses a trunk link. | |
| ARP (Address Resolution Protocol) | A Layer 2 protocol used to map a known Layer 3 IPv4 address to an unknown Layer 2 MAC address using broadcast requests. | |
| BPDU (Bridge Protocol Data Unit) | Multicast frames sent by switches running Spanning Tree Protocol (STP) to communicate topology changes and elect a Root Bridge. | |
| CSMA/CD | Carrier Sense Multiple Access with Collision Detection. The legacy access method used by early half-duplex Ethernet hubs to manage traffic collisions. | |
| DORA Process | The four-step negotiation process for DHCP: Discover, Offer, Request, and Acknowledge. |
F - J
| Term / Acronym | Tags | Definition Summary |
|---|---|---|
| FHRP (First Hop Redundancy Protocol) | A family of protocols (like HSRP and VRRP) that allow multiple physical routers to share a single virtual IP address to provide default gateway redundancy. | |
| Frame | The Protocol Data Unit (PDU) at Layer 2 of the OSI model. It encapsulates the Layer 3 packet with source and destination MAC addresses. |
K - O
| Term / Acronym | Tags | Definition Summary |
|---|---|---|
| LLDP (Link Layer Discovery Protocol) | An open-standard (IEEE 802.1AB) Layer 2 protocol used by network devices to advertise their identity, capabilities, and neighbors. | |
| Native VLAN | The specific VLAN on an 802.1Q trunk that carries untagged traffic. Must match on both ends of the trunk to prevent spanning tree loops. | |
| OSPF (Open Shortest Path First) | A link-state interior gateway routing protocol that uses the Dijkstra algorithm to calculate the fastest path through a network based on bandwidth cost. |
P - T
| Term / Acronym | Tags | Definition Summary |
|---|---|---|
| Packet | The Protocol Data Unit (PDU) at Layer 3 of the OSI model, containing the source and destination IP addresses. | |
| PoE (Power over Ethernet) | A technology that allows standard Ethernet cables to deliver both data and electrical power to devices like VoIP phones and wireless access points. | |
| SLAAC | Stateless Address Autoconfiguration. Allows an IPv6 client to automatically generate its own IP address using Router Advertisements, without needing a DHCPv6 server. | |
| STP (Spanning Tree Protocol) | A Layer 2 loop-prevention protocol that intentionally blocks redundant physical links to ensure a loop-free topology. |
U - Z
| Term / Acronym | Tags | Definition Summary |
|---|---|---|
| UDP (User Datagram Protocol) | A connectionless Layer 4 transport protocol that prioritizes speed over reliability. Used heavily for voice, video, and DNS traffic. | |
| VLAN (Virtual Local Area Network) | A logical grouping of network devices that acts as its own independent broadcast domain, regardless of physical physical switch placement. |