VOCABULARY
Networking Guide - Vocabulary & Glossary
Section titled “Networking Guide - Vocabulary & Glossary”This document provides a comprehensive glossary of networking terms, acronyms, and their full forms used throughout this guide.
Table of Contents
Section titled “Table of Contents”- OSI Model Terms
- TCP/IP & Protocol Terms
- IP Addressing Terms
- Subnetting Terms
- DNS Terms
- DHCP Terms
- NAT & PAT Terms
- Routing Terms
- Firewall Terms
- VPN Terms
- Wireless Terms
- Load Balancing Terms
- VLAN Terms
- Cloud Networking Terms
- General Networking Terms
OSI Model Terms
Section titled “OSI Model Terms”| Term | Full Form | Description |
|---|---|---|
| OSI | Open Systems Interconnection | Reference model for network communication |
| OSI Model | Open Systems Interconnection Model | 7-layer conceptual model for networking |
| PDU | Protocol Data Unit | Data unit at each OSI layer |
| Application Layer | Layer 7 | Top layer where user applications interact with network |
| Presentation Layer | Layer 6 | Data translation and encryption |
| Session Layer | Layer 5 | Session management between applications |
| Transport Layer | Layer 4 | End-to-end communication, reliability |
| Network Layer | Layer 3 | Routing and logical addressing |
| Data Link Layer | Layer 2 | Physical addressing, MAC addresses |
| Physical Layer | Layer 1 | Physical transmission of bits |
| L1 | Layer 1 | Physical layer (see Physical Layer) |
| L2 | Layer 2 | Data link layer (see Data Link Layer) |
| L3 | Layer 3 | Network layer (see Network Layer) |
| L4 | Layer 4 | Transport layer (see Transport Layer) |
| L5 | Layer 5 | Session layer (see Session Layer) |
| L6 | Layer 6 | Presentation layer (see Presentation Layer) |
| L7 | Layer 7 | Application layer (see Application Layer) |
TCP/IP & Protocol Terms
Section titled “TCP/IP & Protocol Terms”| Term | Full Form | Description |
|---|---|---|
| TCP | Transmission Control Protocol | Connection-oriented, reliable transport protocol |
| UDP | User Datagram Protocol | Connectionless, unreliable transport protocol |
| IP | Internet Protocol | Network layer addressing and routing protocol |
| HTTP | HyperText Transfer Protocol | Application protocol for web traffic |
| HTTPS | HTTP Secure | HTTP with TLS/SSL encryption |
| FTP | File Transfer Protocol | Protocol for file transfers |
| SSH | Secure Shell | Secure remote access protocol |
| SMTP | Simple Mail Transfer Protocol | Email sending protocol |
| POP3 | Post Office Protocol v3 | Email retrieval protocol |
| IMAP | Internet Message Access Protocol | Email access protocol |
| DNS | Domain Name System | Domain name resolution service |
| DHCP | Dynamic Host Configuration Protocol | Automatic IP configuration |
| SNMP | Simple Network Management Protocol | Network management and monitoring |
| ICMP | Internet Control Message Protocol | Network diagnostic and error messaging |
| ARP | Address Resolution Protocol | Maps IP to MAC addresses |
| RARP | Reverse ARP | Maps MAC to IP addresses |
| IGMP | Internet Group Management Protocol | Multicast group management |
| MPLS | Multiprotocol Label Switching | High-performance routing method |
| TLS | Transport Layer Security | Encryption protocol |
| SSL | Secure Sockets Layer | Predecessor to TLS |
| FTP | File Transfer Protocol | Protocol for file transfers |
| SFTP | SSH File Transfer Protocol | Secure file transfer protocol |
| SSH | Secure Shell | Encrypted remote access protocol |
| Telnet | Telecommunication Network | Unencrypted remote access (deprecated) |
| IRC | Internet Relay Chat | Real-time text chat protocol |
| LDAP | Lightweight Directory Access Protocol | Directory services protocol |
| SMB | Server Message Block | Windows file sharing protocol |
| NFS | Network File System | Unix/Linux file sharing protocol |
| RPC | Remote Procedure Call | Distributed computing protocol |
IP Addressing Terms
Section titled “IP Addressing Terms”| Term | Full Form | Description |
|---|---|---|
| IP | Internet Protocol | Core network layer protocol |
| IPv4 | Internet Protocol version 4 | 32-bit IP addressing (e.g., 192.168.1.1) |
| IPv6 | Internet Protocol version 6 | 128-bit IP addressing |
| IP Address | Internet Protocol Address | Numerical network identifier |
| Public IP | Public Internet Protocol Address | Globally unique IP address |
| Private IP | Private Internet Protocol Address | Internal network IP (RFC 1918) |
| Static IP | Static Internet Protocol Address | Manually assigned, doesn’t change |
| Dynamic IP | Dynamic Internet Protocol Address | Automatically assigned, can change |
| DHCP | Dynamic Host Configuration Protocol | Automatic IP assignment |
| MAC Address | Media Access Control Address | Physical hardware address |
| NIC | Network Interface Card | Hardware for network connection |
| ARP | Address Resolution Protocol | IP to MAC resolution |
| RARP | Reverse Address Resolution Protocol | MAC to IP resolution |
| NAT | Network Address Translation | Private to public IP translation |
| CIDR | Classless Inter-Domain Routing | IP address notation (e.g., /24) |
| /8 | Slash 8 | CIDR notation for Class A (16M addresses) |
| /16 | Slash 16 | CIDR notation for Class B (65K addresses) |
| /24 | Slash 24 | CIDR notation for Class C (256 addresses) |
| Subnet Mask | Subnet Mask | Defines network/host portions of IP |
| Default Gateway | Default Gateway | Router for external traffic |
| DNS Server | Domain Name System Server | Resolves domain names to IPs |
| Loopback | Loopback Address | 127.0.0.1 - self-referencing IP |
| APIPA | Automatic Private IP Addressing | 169.254.0.0/16 - link-local addresses |
Subnetting Terms
Section titled “Subnetting Terms”| Term | Full Form | Description |
|---|---|---|
| Subnet | Subnetwork | Smaller network segment |
| Subnetting | Subnetting | Dividing network into smaller subnets |
| VLSM | Variable Length Subnet Masking | Subnets of different sizes |
| CIDR | Classless Inter-Domain Routing | Address allocation method |
| Supernetting | Supernetting | Combining smaller networks |
| Network Address | Network Address | First IP in subnet (identifies the network) |
| Broadcast Address | Broadcast Address | Last IP in subnet (sends to all hosts) |
| Host Address | Host Address | Usable IP addresses in subnet |
| Subnet Mask | Subnet Mask | Determines network/host boundary |
| Network Bits | Network Bits | Bits representing network portion |
| Host Bits | Host Bits | Bits representing host portion |
| Prefix Length | Prefix Length | CIDR notation (e.g., /24) |
| Borrowed Bits | Borrowed Bits | Bits taken from host for subnets |
| Valid Hosts | Valid Hosts | Usable IP addresses in subnet |
| Power of 2 | Power of 2 | Calculation: 2^n for subnets/hosts |
| CIDR Block | CIDR Block | Range of IP addresses in CIDR notation |
| IP Range | IP Range | Start and end IP addresses |
DNS Terms
Section titled “DNS Terms”| Term | Full Form | Description |
|---|---|---|
| DNS | Domain Name System | Translates domain names to IP addresses |
| FQDN | Fully Qualified Domain Name | Complete domain name (e.g., www.example.com.) |
| TLD | Top-Level Domain | Last part of domain (.com, .org, .net) |
| ccTLD | Country Code Top-Level Domain | Country-specific TLD (.uk, .de) |
| gTLD | Generic Top-Level Domain | General TLD (.com, .org, .net) |
| Root Server | Root DNS Server | Top-level DNS server (.) |
| TLD Server | Top-Level Domain Server | Manages TLD records |
| Authoritative DNS | Authoritative DNS Server | Has actual zone records |
| Recursive DNS | Recursive DNS Server | Resolves queries for clients |
| DNS Resolver | DNS Resolver | Client’s DNS server (usually ISP) |
| DNS Cache | DNS Cache | Temporary stored DNS records |
| TTL | Time To Live | How long DNS record is cached |
| A Record | Address Record | Maps domain to IPv4 address |
| AAAA Record | Quad A Record | Maps domain to IPv6 address |
| CNAME | Canonical Name Record | Creates alias to another domain |
| MX Record | Mail Exchange Record | Specifies mail servers |
| NS Record | Name Server Record | Delegates DNS zone |
| SOA Record | Start of Authority Record | Zone administrative info |
| TXT Record | Text Record | Stores arbitrary text data |
| PTR Record | Pointer Record | Reverse DNS lookup |
| SRV Record | Service Record | Specifies service location |
| CAA Record | Certification Authority Authorization | Specifies allowed CAs |
| DNSSEC | DNS Security Extensions | Adds security to DNS |
| DNS Query | DNS Query | Request for DNS resolution |
| Recursive Query | Recursive Query | Full resolution by DNS server |
| Iterative Query | Iterative Query | Step-by-step resolution |
| DNS Zone | DNS Zone | Portion of DNS namespace |
| Zone Transfer | Zone Transfer | Copying DNS zone data |
| AXFR | Authoritative Transfer | Full zone transfer |
| IXFR | Incremental Zone Transfer | Partial zone transfer |
DHCP Terms
Section titled “DHCP Terms”| Term | Full Form | Description |
|---|---|---|
| DHCP | Dynamic Host Configuration Protocol | Automatic IP configuration |
| DORA | Discover, Offer, Request, Acknowledge | Four-step DHCP process |
| DHCP Server | DHCP Server | Assigns IP addresses to clients |
| DHCP Client | DHCP Client | Requests IP configuration |
| IP Lease | IP Lease | Temporary assignment of IP address |
| Lease Time | Lease Time | Duration of IP address assignment |
| DHCP Scope | DHCP Scope | Range of IP addresses for assignment |
| DHCP Pool | DHCP Pool | Collection of available IPs |
| Reservation | DHCP Reservation | Fixed IP for specific MAC |
| Scope Options | DHCP Scope Options | DNS, gateway, etc. |
| DHCP Relay | DHCP Relay Agent | Forwards DHCP across routers |
| IP Helper | IP Helper | Cisco term for DHCP relay |
| DHCPNAK | DHCP Negative Acknowledgment | Server rejects request |
| DHCPDISCOVER | DHCP Discover | Client broadcasts to find server |
| DHCPOFFER | DHCP Offer | Server offers IP to client |
| DHCPREQUEST | DHCP Request | Client requests offered IP |
| DHCPACK | DHCP Acknowledgment | Server confirms lease |
| DHCPDECLINE | DHCP Decline | Client rejects offered IP |
| DHCPRELEASE | DHCP Release | Client releases IP early |
| DHCPINFORM | DHCP Inform | Client requests configuration |
| T1 Time | Renewal Time | 50% of lease - renewal attempt |
| T2 Time | Rebinding Time | 87.5% of lease - rebroadcast |
| BOOTP | Bootstrap Protocol | Predecessor to DHCP |
| PXE | Preboot Execution Environment | Network boot protocol |
NAT & PAT Terms
Section titled “NAT & PAT Terms”| Term | Full Form | Description |
|---|---|---|
| NAT | Network Address Translation | Translates private to public IPs |
| PAT | Port Address Translation | Many-to-one NAT using ports |
| SNAT | Source Network Address Translation | Translates source IP |
| DNAT | Destination Network Address Translation | Translates destination IP |
| Static NAT | Static NAT | One-to-one IP mapping |
| Dynamic NAT | Dynamic NAT | Many-to-many IP mapping |
| NAT Overload | NAT Overload | See PAT |
| Masquerading | IP Masquerading | Linux term for PAT |
| Port Forwarding | Port Forwarding | Redirects port to internal host |
| DMZ | Demilitarized Zone | Isolated network for public services |
| Hairpinning | NAT Hairpinning | Traffic exiting same interface it entered |
| NAT Traversal | NAT Traversal | Techniques to work through NAT |
| Full Cone NAT | Full Cone NAT | Least restrictive NAT type |
| Restricted Cone NAT | Restricted Cone NAT | Restricts by IP only |
| Port-Restricted Cone NAT | Port-Restricted Cone NAT | Restricts by IP and port |
| Symmetric NAT | Symmetric NAT | Most restrictive, port depends on destination |
| STUN | Session Traversal Utilities for NAT | NAT type detection |
| TURN | Traversal Using Relays around NAT | Relay server for NAT traversal |
| ICE | Interactive Connectivity Establishment | NAT traversal method |
| Hole Punching | NAT Hole Punching | Creating pinholes in NAT |
| UPnP | Universal Plug and Play | Automatic port forwarding |
| PCP | Port Control Protocol | Modern port forwarding protocol |
Routing Terms
Section titled “Routing Terms”| Term | Full Form | Description |
|---|---|---|
| Router | Router | Device that forwards packets between networks |
| Routing Table | Routing Table | Database of routes |
| Default Route | Default Route | Catch-all route (0.0.0.0/0) |
| Static Route | Static Route | Manually configured route |
| Dynamic Route | Dynamic Route | Learned via routing protocol |
| Route Metric | Route Metric | Cost value for route selection |
| Routing Protocol | Routing Protocol | Protocol for dynamic routing |
| IGP | Interior Gateway Protocol | Routing within an AS |
| EGP | Exterior Gateway Protocol | Routing between ASes |
| AS | Autonomous System | Collection of networks under one administration |
| BGP | Border Gateway Protocol | Internet routing protocol |
| OSPF | Open Shortest Path First | Link-state IGP |
| EIGRP | Enhanced Interior Gateway Routing Protocol | Cisco hybrid IGP |
| RIP | Routing Information Protocol | Distance-vector IGP |
| IS-IS | Intermediate System to Intermediate System | Link-state IGP |
| LSA | Link State Advertisement | OSPF routing information |
| LSDB | Link State Database | OSPF topology database |
| SPF | Shortest Path First | OSPF path calculation algorithm |
| ABR | Area Border Router | OSPF router connecting areas |
| ASBR | Autonomous System Boundary Router | OSPF router connecting to other AS |
| DR | Designated Router | OSPF representative on multi-access network |
| BDR | Backup Designated Router | OSPF DR backup |
| Area 0 | Backbone Area | OSPF backbone area |
| Neighbor | Routing Neighbor | Adjacent router |
| Adjacency | Routing Adjacency | Formed between neighboring routers |
| Convergence | Network Convergence | All routers have consistent routing info |
| Loop Prevention | Loop Prevention | Mechanisms to prevent routing loops |
| Split Horizon | Split Horizon | Routing loop prevention technique |
| Poison Reverse | Poison Reverse | Advertises infinite metric |
| Count to Infinity | Count to Infinity | Routing loop problem in distance-vector |
| Maximum Hop Count | Maximum Hop Count | RIP’s loop prevention (16 hops) |
| Route Summarization | Route Summarization | Combining routes into single advertisement |
| Route Aggregation | Route Aggregation | See Route Summarization |
| Longest Match | Longest Prefix Match | Most specific route wins |
| Administrative Distance | Administrative Distance | Route preference in Cisco |
| Route Preference | Route Preference | Route preference in Linux |
| Next Hop | Next Hop | Next router in path |
| Gateway | Gateway | Router interface |
| Routing Cache | Routing Cache | Cached routing decisions |
Firewall Terms
Section titled “Firewall Terms”| Term | Full Form | Description |
|---|---|---|
| Firewall | Firewall | Network security device |
| Packet Filter | Packet Filter | Basic firewall filtering |
| Stateful Firewall | Stateful Firewall | Tracks connection state |
| Stateless Firewall | Stateless Firewall | Doesn’t track connections |
| Application Firewall | Application Firewall | Layer 7 filtering |
| NGFW | Next-Generation Firewall | Advanced firewall with DPI |
| WAF | Web Application Firewall | Protects web applications |
| UTM | Unified Threat Management | All-in-one security appliance |
| ACL | Access Control List | List of allow/deny rules |
| Rule | Firewall Rule | Individual filter condition |
| Policy | Security Policy | Set of firewall rules |
| Allow | Allow | Permit traffic |
| Deny | Deny | Block traffic |
| Drop | Drop | Silently discard packet |
| Reject | Reject | Discard and send error |
| Log | Log | Record firewall event |
| Inbound | Inbound | Traffic entering network |
| Outbound | Outbound | Traffic leaving network |
| Ingress | Ingress | See Inbound |
| Egress | Egress | See Outbound |
| Port | Port | Logical connection point |
| Protocol | Protocol | TCP, UDP, ICMP, etc. |
| Source IP | Source IP | Originating IP address |
| Destination IP | Destination IP | Target IP address |
| Source Port | Source Port | Originating port |
| Destination Port | Destination Port | Target port |
| SYN | Synchronize | TCP connection start flag |
| ACK | Acknowledgment | TCP confirmation flag |
| FIN | Finish | TCP connection end flag |
| RST | Reset | TCP connection reset |
| PSH | Push | TCP push data flag |
| URG | Urgent | TCP urgent data flag |
| Stateful Inspection | Stateful Inspection | Tracks connection state |
| Deep Packet Inspection | Deep Packet Inspection | Examines packet content |
| DMZ | Demilitarized Zone | Isolated network segment |
| Zone | Firewall Zone | Group of interfaces with same policy |
| iptables | iptables | Linux packet filtering tool |
| nftables | nftables | Linux packet filtering tool (newer) |
| firewalld | firewalld | Dynamic firewall manager |
| UFW | Uncomplicated Firewall | Simplified iptables |
| pf | Packet Filter | BSD/macOS firewall |
| UTM | Unified Threat Management | Multi-function security |
VPN Terms
Section titled “VPN Terms”| Term | Full Form | Description |
|---|---|---|
| VPN | Virtual Private Network | Encrypted tunnel over public network |
| Remote Access VPN | Remote Access VPN | Individual user connection |
| Site-to-Site VPN | Site-to-Site VPN | Network-to-network connection |
| SSL VPN | SSL VPN | VPN using SSL/TLS |
| IPSec | IP Security | VPN encryption protocol suite |
| PPTP | Point-to-Point Tunneling Protocol | Legacy VPN protocol |
| L2TP | Layer 2 Tunneling Protocol | VPN tunneling protocol |
| L2TP/IPsec | L2TP with IPsec | Combined L2TP and IPsec |
| OpenVPN | OpenVPN | Open-source VPN solution |
| WireGuard | WireGuard | Modern, lightweight VPN |
| Tunnel | VPN Tunnel | Encrypted connection path |
| Encapsulation | Encapsulation | Wrapping data in protocol headers |
| Encryption | Encryption | Data encoding for security |
| Tunnel Mode | IPsec Tunnel Mode | Encrypts entire IP packet |
| Transport Mode | IPsec Transport Mode | Encrypts only payload |
| AH | Authentication Header | IPsec authentication |
| ESP | Encapsulating Security Payload | IPsec encryption |
| IKE | Internet Key Exchange | IPsec key exchange |
| SA | Security Association | IPsec security parameters |
| Pre-Shared Key | Pre-Shared Key | Shared secret for encryption |
| Certificate | Digital Certificate | Identity verification |
| PKI | Public Key Infrastructure | Certificate management system |
| Split Tunneling | Split Tunneling | Only tunnel specific traffic |
| Full Tunnel | Full Tunnel | All traffic through VPN |
| Dead Peer Detection | Dead Peer Detection | Detect VPN peer failure |
| NAT Traversal | NAT Traversal | Work through NAT devices |
| MPLS VPN | MPLS VPN | VPN using MPLS backbone |
| VPDN | Virtual Private Dialup Network | Dial-up VPN |
| Tunnel Interface | Tunnel Interface | Virtual VPN interface |
Wireless Terms
Section titled “Wireless Terms”| Term | Full Form | Description |
|---|---|---|
| WiFi | Wireless Fidelity | Wireless networking technology |
| WLAN | Wireless Local Area Network | Wireless network |
| SSID | Service Set Identifier | Wireless network name |
| BSSID | Basic Service Set Identifier | Access Point MAC address |
| ESSID | Extended Service Set Identifier | Multiple APs network name |
| AP | Access Point | Wireless network device |
| STA | Station | Wireless client device |
| IBSS | Independent Basic Service Set | Ad-hoc mode |
| BSS | Basic Service Set | Infrastructure mode |
| ESS | Extended Service Set | Multiple BSS |
| Ad-Hoc | Ad-Hoc Mode | Device-to-device network |
| Infrastructure Mode | Infrastructure Mode | AP-based network |
| 2.4 GHz | 2.4 Gigahertz | Common WiFi frequency band |
| 5 GHz | 5 Gigahertz | Higher frequency WiFi band |
| 6 GHz | 6 Gigahertz | WiFi 6E frequency band |
| Channel | Wireless Channel | Specific frequency within band |
| Channel Width | Channel Width | Bandwidth of wireless channel |
| Bandwidth | Bandwidth | Data transmission capacity |
| Frequency | Frequency | Radio wave oscillation rate |
| Signal Strength | Signal Strength | Received signal power |
| RSSI | Received Signal Strength Indicator | Signal power measurement |
| dBm | Decibel-milliwatts | Power measurement unit |
| SNR | Signal-to-Noise Ratio | Signal quality measurement |
| Modulation | Modulation | Encoding data on radio wave |
| QAM | Quadrature Amplitude Modulation | Complex modulation |
| OFDM | Orthogonal Frequency-Division Multiplexing | Multi-carrier modulation |
| MU-MIMO | Multi-User MIMO | Multiple simultaneous users |
| MIMO | Multiple Input Multiple Output | Multiple antennas |
| Beamforming | Beamforming | Signal direction optimization |
| 802.11a | IEEE 802.11a | WiFi standard (5 GHz, 54 Mbps) |
| 802.11b | IEEE 802.11b | WiFi standard (2.4 GHz, 11 Mbps) |
| 802.11g | IEEE 802.11g | WiFi standard (2.4 GHz, 54 Mbps) |
| 802.11n | IEEE 802.11n | WiFi standard (WiFi 4) |
| 802.11ac | IEEE 802.11ac | WiFi standard (WiFi 5) |
| 802.11ax | IEEE 802.11ax | WiFi standard (WiFi 6) |
| WiFi 4 | WiFi 4 | 802.11n marketing name |
| WiFi 5 | WiFi 5 | 802.11ac marketing name |
| WiFi 6 | WiFi 6 | 802.11ax marketing name |
| WiFi 6E | WiFi 6E | 802.11ax with 6 GHz |
| WEP | Wired Equivalent Privacy | Legacy WiFi security |
| WPA | WiFi Protected Access | Improved WiFi security |
| WPA2 | WiFi Protected Access II | Current standard security |
| WPA3 | WiFi Protected Access III | Newest WiFi security |
| PSK | Pre-Shared Key | WiFi password |
| AES | Advanced Encryption Standard | Encryption algorithm |
| TKIP | Temporal Key Integrity Protocol | Legacy encryption |
| CCMP | Counter Mode with CBC-MAC Protocol | WPA2 encryption |
| SAE | Simultaneous Authentication of Equals | WPA3 authentication |
| PMF | Protected Management Frames | WPA2 security feature |
| WPS | WiFi Protected Setup | Easy setup method |
Load Balancing Terms
Section titled “Load Balancing Terms”| Term | Full Form | Description |
|---|---|---|
| LB | Load Balancer | Distributes traffic across servers |
| SLB | Server Load Balancer | See Load Balancer |
| CLB | Classic Load Balancer | AWS legacy LB |
| ALB | Application Load Balancer | Layer 7 LB |
| NLB | Network Load Balancer | Layer 4 LB |
| GLB | Gateway Load Balancer | Third-party appliance LB |
| Layer 4 LB | Layer 4 Load Balancer | Transport layer balancing |
| Layer 7 LB | Layer 7 Load Balancer | Application layer balancing |
| L4 | Layer 4 | Transport layer |
| L7 | Layer 7 | Application layer |
| Round Robin | Round Robin | Sequential distribution |
| Least Connections | Least Connections | Fewest active connections |
| Least Response Time | Least Response Time | Fastest response |
| IP Hash | IP Hash | Source IP-based distribution |
| Weighted | Weighted | Based on server capacity |
| Random | Random | Random distribution |
| Health Check | Health Check | Server availability test |
| Active Health Check | Active Health Check | Proactive testing |
| Passive Health Check | Passive Health Check | On-request testing |
| HTTP Check | HTTP Health Check | Web-based health test |
| TCP Check | TCP Health Check | Port-based health test |
| ICMP Check | ICMP Health Check | Ping-based health test |
| SSL Termination | SSL Termination | Decrypt at load balancer |
| SSL Offloading | SSL Offloading | See SSL Termination |
| Session Persistence | Session Persistence | Same server for session |
| Sticky Session | Sticky Session | See Session Persistence |
| Cookie Insert | Cookie Insert | LB adds session cookie |
| Cookie Prefix | Cookie Prefix | Encoded session in cookie |
| Source IP Affinity | Source IP Affinity | Same IP to same server |
| Server Pool | Server Pool | Group of backend servers |
| Backend | Backend | Servers behind load balancer |
| Frontend | Frontend | Client-facing side |
| Backend Server | Backend Server | Actual application server |
| Pool Member | Pool Member | Individual server in pool |
| Virtual IP | Virtual IP | Shared IP for pool |
| VIP | Virtual IP | See Virtual IP |
| HA | High Availability | Redundant systems |
| Failover | Failover | Automatic backup activation |
| Active-Active | Active-Active | Multiple active instances |
| Active-Passive | Active-Passive | Primary and standby |
| Quorum | Quorum | Required majority for operation |
| Keepalived | Keepalived | Linux HA solution |
| VRRP | Virtual Router Redundancy Protocol | Router HA protocol |
| PAC | Proxy Auto-Configuration | Browser proxy settings |
VLAN Terms
Section titled “VLAN Terms”| Term | Full Form | Description |
|---|---|---|
| VLAN | Virtual Local Area Network | Logical network segment |
| VLAN ID | VLAN Identifier | 12-bit VLAN number (1-4094) |
| VLAN Tag | VLAN Tag | 802.1Q marker in frame |
| 802.1Q | IEEE 802.1Q | VLAN tagging standard |
| Native VLAN | Native VLAN | Untagged traffic on trunk |
| Voice VLAN | Voice VLAN | Separate VLAN for VoIP |
| Management VLAN | Management VLAN | Network device management |
| Data VLAN | Data VLAN | User traffic VLAN |
| Private VLAN | Private VLAN | Port isolation within VLAN |
| Community VLAN | Community VLAN | PVLAN with inter-port communication |
| Isolated VLAN | Isolated VLAN | PVLAN with no inter-port communication |
| Trunk | Trunk Link | Carries multiple VLANs |
| Trunk Port | Trunk Port | Switch port for trunk |
| Access Port | Access Port | Single VLAN port |
| Uplink | Uplink | Connection to another switch |
| Downlink | Downlink | Connection to end devices |
| VTP | VLAN Trunking Protocol | Cisco VLAN management |
| VTP Domain | VTP Domain | Group of switches with same VTP |
| VTP Server | VTP Server | Creates/modifies VLANs |
| VTP Client | VTP Client | Learns VLANs from server |
| VTP Transparent | VTP Transparent | Independent VLAN database |
| DTP | Dynamic Trunking Protocol | Cisco auto-trunking |
| VLAN Trunking | VLAN Trunking | Carrying multiple VLANs |
| Inter-VLAN Routing | Inter-VLAN Routing | Routing between VLANs |
| Router-on-a-Stick | Router-on-a-Stick | Single interface, multiple subinterfaces |
| L3 Switch | Layer 3 Switch | Switch with routing capability |
| SVI | Switch Virtual Interface | Virtual router interface |
| VLAN Interface | VLAN Interface | See SVI |
| Bridge | Bridge | Layer 2 forwarding device |
| Bridge VLAN | Bridge VLAN | Bridge member ports |
| VXLAN | Virtual Extensible LAN | Layer 3 overlay for VLANs |
| VNI | VXLAN Network Identifier | 24-bit VXLAN ID |
| NVGRE | Network Virtualization using GRE | Microsoft overlay technology |
| Geneve | Generic Network Virtualization Encapsulation | Modern overlay protocol |
| MSTP | Multiple Spanning Tree Protocol | VLAN-aware STP |
| STP | Spanning Tree Protocol | Loop prevention protocol |
| RSTP | Rapid Spanning Tree Protocol | Fast STP |
| PVST | Per-VLAN Spanning Tree | Cisco per-VLAN STP |
Cloud Networking Terms
Section titled “Cloud Networking Terms”| Term | Full Form | Description |
|---|---|---|
| VPC | Virtual Private Cloud | Isolated virtual network in cloud |
| VNet | Virtual Network | Azure’s VPC equivalent |
| Subnet | Cloud Subnet | Logical subdivision of VPC |
| Public Subnet | Public Subnet | Has internet access |
| Private Subnet | Private Subnet | No direct internet |
| Availability Zone | Availability Zone | Isolated data center |
| AZ | Availability Zone | See Availability Zone |
| Region | Cloud Region | Geographic cloud area |
| Edge Location | Edge Location | CDN cache location |
| Internet Gateway | Internet Gateway | VPC internet access |
| Egress-Only IGW | Egress-Only Internet Gateway | IPv6 internet access |
| NAT Gateway | NAT Gateway | Managed NAT service |
| NAT Instance | NAT Instance | Self-managed NAT |
| Security Group | Security Group | Instance-level firewall |
| NACL | Network Access Control List | Subnet-level firewall |
| SG | Security Group | See Security Group |
| Network ACL | Network Access Control List | See NACL |
| Route Table | Route Table | Determines traffic path |
| Network ACL | Network Access Control List | Stateless subnet rules |
| Peering | VPC Peering | Direct VPC connection |
| VPC Peering | VPC Peering | See Peering |
| Transit Gateway | Transit Gateway | Central hub for VPCs |
| TGW | Transit Gateway | See Transit Gateway |
| Direct Connect | Direct Connect | Dedicated AWS connection |
| ExpressRoute | ExpressRoute | Azure dedicated connection |
| Cloud VPN | Cloud VPN | VPN to cloud |
| VPN Connection | VPN Connection | IPSec tunnel to VPC |
| Customer Gateway | Customer Gateway | On-premises VPN device |
| Virtual Private Gateway | Virtual Private Gateway | AWS VPN endpoint |
| VPG | Virtual Private Gateway | See Virtual Private Gateway |
| CGW | Customer Gateway | See Customer Gateway |
| AWS VPN | AWS VPN | AWS VPN service |
| Azure VPN Gateway | Azure VPN Gateway | Azure VPN service |
| Cloud DNS | Cloud DNS | Managed DNS service |
| Private DNS | Private DNS | Internal DNS resolution |
| Private Hosted Zone | Private Hosted Zone | Route 53 private zone |
| Route 53 | Amazon Route 53 | AWS DNS service |
| Cloud CDN | Cloud CDN | Content delivery network |
| CloudFront | Amazon CloudFront | AWS CDN |
| ELB | Elastic Load Balancing | AWS load balancer |
| ALB | Application Load Balancer | Layer 7 AWS LB |
| NLB | Network Load Balancer | Layer 4 AWS LB |
| Auto Scaling | Auto Scaling | Automatic capacity adjustment |
| ASG | Auto Scaling Group | Collection of instances |
| IAM Role | IAM Role | Cloud access permissions |
| Instance Profile | Instance Profile | EC2 IAM role |
| Placement Group | Placement Group | Cluster of instances |
| ENI | Elastic Network Interface | Virtual network interface |
| EIP | Elastic IP | Static public IP |
| Secondary IP | Secondary IP | Additional IP address |
| VPC Endpoint | VPC Endpoint | Private connection to service |
| Gateway Endpoint | Gateway Endpoint | S3/DynamoDB endpoint |
| Interface Endpoint | Interface Endpoint | PrivateLink endpoint |
| PrivateLink | PrivateLink | AWS private connectivity |
General Networking Terms
Section titled “General Networking Terms”| Term | Full Form | Description |
|---|---|---|
| LAN | Local Area Network | Local network (building/campus) |
| WAN | Wide Area Network | Geographic network |
| MAN | Metropolitan Area Network | City-scale network |
| PAN | Personal Area Network | Personal device network |
| CAN | Campus Area Network | University/campus network |
| SAN | Storage Area Network | Dedicated storage network |
| VPN | Virtual Private Network | Encrypted tunnel network |
| Bandwidth | Bandwidth | Data transfer capacity |
| Latency | Latency | Data transfer delay |
| Jitter | Jitter | Variation in latency |
| Packet Loss | Packet Loss | Dropped data packets |
| Throughput | Throughput | Actual data transfer rate |
| MTU | Maximum Transmission Unit | Largest packet size |
| Jumbo Frame | Jumbo Frame | Large MTU (9000 bytes) |
| Duplex | Duplex | Communication direction |
| Full Duplex | Full Duplex | Bidirectional communication |
| Half Duplex | Half Duplex | One-way communication |
| Collision | Network Collision | Data packet collision |
| Collision Domain | Collision Domain | Area where collisions occur |
| Broadcast Domain | Broadcast Domain | Area receiving broadcasts |
| CSMA/CD | Carrier Sense Multiple Access with Collision Detection | Ethernet access method |
| MAC Address | Media Access Control Address | Physical address |
| OUI | Organizationally Unique Identifier | MAC address manufacturer ID |
| Uplink | Uplink | Upstream connection |
| Downlink | Downlink | Downstream connection |
| Patch Panel | Patch Panel | Cable management panel |
| Rack | Server Rack | Equipment mounting frame |
| Switch | Network Switch | Multi-port bridging device |
| Router | Network Router | Layer 3 forwarding device |
| Gateway | Network Gateway | Network entry/exit point |
| Hub | Network Hub | Multi-port repeater (deprecated) |
| Bridge | Network Bridge | Connects two network segments |
| NIC | Network Interface Card | Network adapter |
| GBIC | Gigabit Interface Converter | Swappable transceiver |
| SFP | Small Form-Factor Pluggable | Optical transceiver |
| SFP+ | SFP Plus | 10G transceiver |
| QSFP | Quad SFP | 40G transceiver |
| DAC | Direct Attach Cable | Twinaxial cable |
| AOC | Active Optical Cable | Optical cable assembly |
| Fiber | Optical Fiber | Glass/plastic cable for light transmission |
| Single Mode | Single Mode Fiber | Long-distance fiber |
| Multi Mode | Multi Mode Fiber | Short-distance fiber |
| UTP | Unshielded Twisted Pair | Common copper cable |
| STP | Shielded Twisted Pair | Shielded copper cable |
| Cat5e | Category 5e | 1 Gbps copper cable |
| Cat6 | Category 6 | 10 Gbps copper cable |
| Cat6a | Category 6a | 10 Gbps, 55m copper cable |
| Cat7 | Category 7 | 10 Gbps, shielded copper |
| Cat8 | Category 8 | 25-40 Gbps copper cable |
| PoE | Power over Ethernet | Power over network cable |
| PoE+ | Power over Ethernet Plus | Higher power PoE |
| PoE++ | Power over Ethernet Plus Plus | Highest power PoE |
| UPOE | Universal Power over Ethernet | Cisco PoE standard |
| QoS | Quality of Service | Traffic prioritization |
| TOS | Type of Service | QoS field in IP header |
| DSCP | Differentiated Services Code Point | QoS marking |
| CoS | Class of Service | Layer 2 QoS |
| Traffic Shaping | Traffic Shaping | Rate limiting |
| Traffic Policing | Traffic Policing | Drop or mark exceeding traffic |
| Rate Limiting | Rate Limiting | Bandwidth restriction |
| Port Mirroring | Port Mirroring | Traffic duplication for analysis |
| SPAN | Switched Port Analyzer | Cisco port mirroring |
| RSPAN | Remote SPAN | Remote port mirroring |
| ERSPAN | Encapsulated Remote SPAN | Encrypted remote mirroring |
| NetFlow | NetFlow | Traffic analysis protocol |
| sFlow | sFlow | Sampled flow monitoring |
| IPFIX | IP Flow Information Export | Flow export standard |
| RADIUS | Remote Authentication Dial-In User Service | AAA protocol |
| TACACS+ | Terminal Access Controller Access-Control System Plus | Cisco AAA protocol |
| LDAP | Lightweight Directory Access Protocol | Directory service protocol |
| Kerberos | Kerberos | Network authentication protocol |
| SSO | Single Sign-On | One login for multiple services |
| MFA | Multi-Factor Authentication | Multiple verification methods |
| 2FA | Two-Factor Authentication | Two-step verification |
| 802.1X | IEEE 802.1X | Port-based network access control |
| NAC | Network Access Control | Endpoint security policy |
| ARP Spoofing | ARP Spoofing | ARP poisoning attack |
| MAC Flooding | MAC Flooding | Switch table overflow |
| VLAN Hopping | VLAN Hopping | VLAN attack technique |
| Rogue DHCP | Rogue DHCP | Unauthorized DHCP server |
| DHCP Snooping | DHCP Snooping | DHCP attack prevention |
| DAI | Dynamic ARP Inspection | ARP attack prevention |
| IPSG | IP Source Guard | IP spoofing prevention |
| ACL | Access Control List | Permission list |
| AAA | Authentication, Authorization, Accounting | Security framework |
| RTO | Recovery Time Objective | Max downtime acceptable |
| RPO | Recovery Point Objective | Max data loss acceptable |
| HA | High Availability | Redundant systems |
| DR | Disaster Recovery | Recovery from disasters |
| BCP | Business Continuity Planning | Operational continuity |
| SLA | Service Level Agreement | Service guarantee |
Last Updated: February 2026