Networking(315 terms)
A full list of the Networking terms and explanations covered by ITBGM.
Use the search box below to filter by term name.
Each term links to a page with a more detailed, engineer-oriented explanation.
No terms match "
2.4GHz Band Wireless LAN ☆ A Wi-Fi frequency band that resists obstacles well but is prone to interference from other devices.
2N Redundancy Network Redundancy & Design ☆ A generous redundancy configuration where the full set of required equipment is duplicated.
5GHz Band Wireless LAN ☆ A Wi-Fi frequency band with less interference and higher speed, but weaker against obstacles.
802.1Q Switching ☆ A tagging standard for adding VLAN information to Ethernet frames.
802.1X Authentication & Access Control ☆ A standard that authenticates devices on a per-port basis, used on both wired and wireless LANs.
A Record DNS ☆ A DNS record that maps a domain name to an IPv4 address.
Access Point Wireless LAN ☆ A device that relays wireless devices onto a wired network.
Access Port Switching ☆ A port that belongs to only a single VLAN, used to connect end devices.
Active-Active Load Balancing ☆ A redundancy configuration where multiple systems run simultaneously, also serving as load balancing.
Active-Standby Load Balancing ☆ A redundancy configuration where normally only one system runs, switching to the other on failure.
Administrative Distance Routing ☆ A value indicating the trustworthiness of a route between different routing protocols.
Anycast Address TCP/IP Basics ☆ A communication method that assigns the same address to multiple devices and delivers to the topologically nearest one.
Anycast DNS DNS ☆ A setup where the same IP address is assigned to DNS servers at multiple locations, automatically routing users to the nearest one.
APIPA TCP/IP Basics ☆ A 169.254.0.0/16 address automatically assigned when no DHCP server can be found.
Application Layer OSI Reference Model ☆ OSI layer 7, handling communication for applications the user interacts with directly.
Area 0 Routing ☆ The central backbone area in OSPF to which all other areas connect.
ARP TCP/IP Basics ☆ A protocol that resolves a MAC address on the same segment from an IP address.
ARP Spoofing Troubleshooting ☆ An attack technique that maliciously redirects traffic using forged ARP replies.
AS Number BGP ☆ A number identifying an autonomous system (an organization-level network) on the internet.
AS Path BGP ☆ An attribute showing which autonomous systems a route has passed through, also used for loop detection.
Asymmetric Routing Troubleshooting ☆ A state where outbound and inbound traffic take different routes.
Authoritative DNS Server DNS ☆ A DNS server responsible for returning the official answer for a specific domain.
Auto-negotiation Optical & Physical Layer ☆ A mechanism where two connected devices automatically agree on communication speed and duplex (full/half) settings.
Bandwidth QoS ☆ A metric expressing the maximum amount of data that can be transmitted in a given time.
Bandwidth Control QoS ☆ Controlling the upper limit of bandwidth available per communication.
BDR Routing ☆ OSPF's backup designated router, standing by in case the DR fails.
Beamforming Wireless LAN ☆ A technology that concentrates radio waves in a specific direction to improve communication quality.
BFD Routing ☆ A protocol that detects link failures at millisecond speed.
BGP BGP ☆ A routing protocol that exchanges route information between networks of different organizations.
BGP Convergence BGP ☆ The process by which BGP route information stabilizes after a network change.
BGP Neighbor BGP ☆ A router configured as a partner for exchanging route information over BGP.
BPDU Switching ☆ A control frame exchanged between switches in Spanning Tree.
Bridge Switching ☆ A device that connects two network segments based on MAC addresses.
Broadcast TCP/IP Basics ☆ A communication method that sends to all devices within the same network at once.
Broadcast Domain Switching ☆ The network range that a broadcast reaches.
Broadcast Storm Troubleshooting ☆ A phenomenon where broadcasts multiply endlessly due to a loop and communication becomes impossible.
Cable Tester Troubleshooting ☆ A measuring device that checks LAN cable wiring or breaks.
Captive Portal Wireless LAN ☆ A mechanism that displays an authentication screen in a browser when connecting to a wireless LAN.
CDP Network Management ☆ A Cisco-proprietary protocol for exchanging information between neighboring Cisco devices.
CE Router MPLS & Carrier Technology ☆ A router installed at the customer site that connects to the carrier network.
Channel Bonding Wireless LAN ☆ A technology that combines multiple wireless channels to widen bandwidth.
CIDR TCP/IP Basics ☆ A notation that flexibly expresses an IP address range using a prefix length.
CMTS Access Network ☆ An aggregation device on the CATV operator's side that terminates subscriber cable modems.
CNAME Record DNS ☆ A DNS record that sets one domain name as an alias for another.
Collision Switching ☆ A phenomenon in half-duplex communication where signals clash because multiple devices transmit data at the same time.
Collision Domain Switching ☆ The network range within which communication collisions can occur.
Connection Draining Load Balancing ☆ A mechanism that waits for existing connections to finish before removing a server.
Control Plane SD-WAN & SDN ☆ The part responsible for controlling communication, such as calculating route information.
Convergence (routing) Routing ☆ The state where all routers agree on the current routing information after a change in network topology.
CoS QoS ☆ A value attached to Ethernet frames indicating communication priority.
DAA Access Network ☆ An architecture that distributes some CMTS functions out to the node, closer to subscribers.
DAD IPv6 Details ☆ A mechanism that checks whether an IPv6 address is already in use on the same segment.
Data Link Layer OSI Reference Model ☆ OSI layer 2, which handles communication between neighboring devices using MAC addresses.
Data Plane SD-WAN & SDN ☆ The part that actually forwards packets.
Default Gateway Routing ☆ The address of the device that serves as the exit point out of your own network.
Default Route Advertisement BGP ☆ Advertising a default route to a BGP neighbor.
DHCP TCP/IP Basics ☆ A protocol that automatically distributes network settings such as IP addresses.
DHCP Relay Agent TCP/IP Basics ☆ A function that relays requests to a DHCP server located on a different segment.
DHCP Snooping Authentication & Access Control ☆ A switch security feature that permits DHCP responses only from a legitimate server, filtering out rogue DHCP servers.
DMVPN VPN ☆ A Cisco VPN technology that dynamically builds full-mesh connections between sites.
DNS DNS ☆ A mechanism, like an internet address book, that maps domain names to IP addresses.
DNS Cache DNS ☆ A mechanism that temporarily stores resolved domain name results to reduce repeat queries.
DNS Cache Poisoning DNS ☆ An attack that injects false information into a DNS cache to redirect users to a malicious site.
DNS Round Robin DNS ☆ A load-balancing technique that assigns multiple IP addresses to one domain name and returns them in turn.
DNS Tunneling DNS ☆ A technique that embeds other data within DNS traffic to abuse it as a communication channel.
DNSSEC DNS ☆ An extension that lets DNS response tampering be detected using digital signatures.
DOCSIS Access Network ☆ A communication standard for cable modems that delivers internet access over coaxial cable.
DoH DNS ☆ A method that encrypts DNS queries using HTTPS.
DoT DNS ☆ A method that encrypts DNS queries using TLS.
DR Routing ☆ In an OSPF multi-access network, the router that serves as the central point for exchanging route information.
DSCP QoS ☆ A mechanism that sets a priority value in the header of an IP packet.
DSR Load Balancing ☆ A method where the server returns responses directly to the client, bypassing the load balancer.
Dual Homing Network Redundancy & Design ☆ A configuration that connects a site or device to two separate routes or devices.
Dual Stack IPv6 Details ☆ A method that enables both IPv4 and IPv6 simultaneously on the same device.
Duplex Mismatch Troubleshooting ☆ A problem where connected devices' full-duplex/half-duplex settings don't match, degrading communication quality.
Dynamic ARP Inspection Authentication & Access Control ☆ A switch security feature that validates the contents of ARP packets to prevent ARP spoofing attacks.
Dynamic Routing Routing ☆ A method where route information is automatically exchanged and updated via a routing protocol.
EAP Wireless LAN ☆ An authentication framework used in wireless LANs and elsewhere that supports a variety of authentication methods.
East-West Traffic Data Center Networking ☆ Traffic exchanged between servers within a data center.
eBGP BGP ☆ BGP exchanged between routers with different AS numbers.
ECMP Data Center Networking ☆ A technology that distributes traffic across multiple routes of equal cost.
ECN QoS ☆ A mechanism that notifies both endpoints of network congestion before packets actually need to be dropped.
EIGRP Routing ☆ A Cisco routing protocol combining characteristics of distance-vector and link-state protocols.
ESP VPN ☆ A protocol in IPsec that performs packet encryption and authentication.
Ethernet TCP/IP Basics ☆ The most widely used data-link-layer standard for wired LANs.
EVPN Data Center Networking ☆ A BGP-based technology used to control overlays such as VXLAN.
Extended ACL Authentication & Access Control ☆ An ACL that filters on detailed criteria such as source, destination, and port number.
Failover Load Balancing ☆ A mechanism that automatically switches to a standby system when a failure occurs.
Fiber Optic Cable Optical & Physical Layer ☆ A communication cable made of glass or plastic that transmits data as pulses of light.
Floating Static Route Routing ☆ A backup static route that normally isn't used, activating only when the primary route fails.
Forward Lookup DNS ☆ Looking up an IP address from a domain name.
Fragmentation TCP/IP Basics ☆ Splitting data exceeding the MTU into multiple packets for transmission.
FTTH Access Network ☆ A fiber access method that runs fiber optic cable all the way to the subscriber's home.
Full Duplex / Half Duplex Optical & Physical Layer ☆ A distinction based on whether a communication channel can send and receive data at the same time, or only alternately.
Full-Service Resolver (Caching DNS Server) DNS ☆ A caching DNS server that performs name resolution on behalf of a client.
GLBP Network Redundancy & Design ☆ A Cisco proprietary protocol that provides redundancy for the default gateway across multiple routers while also load-balancing traffic between them.
Global IP Address TCP/IP Basics ☆ An IP address uniquely identified on the internet.
Global Unicast Address IPv6 Details ☆ An IPv6 address uniquely reachable on the internet.
Glue Record DNS ☆ A record used to resolve an authoritative DNS server's own name, avoiding a circular reference.
GRE Tunneling & Overlay ☆ A tunneling technology that encapsulates packets of various protocols within IP for transport.
GSLB Load Balancing ☆ Global load balancing that distributes traffic across multiple geographically distant sites.
Health Check Load Balancing ☆ A mechanism that periodically checks whether a server is operating normally.
HFC Access Network ☆ A CATV network design that uses fiber for the trunk and coaxial cable for the run to subscriber homes.
Hop Count Routing ☆ The number of routers a packet passes through to reach its destination.
HSRP Routing ☆ A Cisco-proprietary protocol for making the default gateway redundant.
Hub Switching ☆ A physical-layer relay device that simply repeats incoming data out to every connected port.
iBGP BGP ☆ BGP exchanged between routers within the same AS number.
ICMP TCP/IP Basics ☆ A protocol used for connectivity checks and error notification, used by ping.
IGMP Multicast ☆ A protocol by which a host informs the network of joining or leaving a multicast group.
IKE VPN ☆ A protocol used in IPsec to safely exchange encryption keys.
IKEv2 VPN ☆ The second version of IKE, the protocol used for key exchange in IPsec VPNs.
IP Address TCP/IP Basics ☆ A number, like an address, that identifies a device on a network.
IPoE Access Network ☆ A newer fiber-internet connection method that carries IP packets directly over Ethernet without using PPP.
IPsec VPN ☆ A group of VPN protocols that encrypt and authenticate at the IP packet level.
IPv4 TCP/IP Basics ☆ The version of IP addressing with a 32-bit address space that's widely used across the internet.
IPv6 TCP/IP Basics ☆ A next-generation IP address standard created to address IPv4 address exhaustion.
IS-IS Routing ☆ A link-state routing protocol, in the same family as OSPF, used to exchange routing information.
Iterative Query DNS ☆ A query method between servers, in which the response points to another DNS server.
Jitter QoS ☆ Variation in the interval at which packets arrive.
Jumbo Frame TCP/IP Basics ☆ An Ethernet frame larger than the standard 1500 bytes.
L2TP VPN ☆ A data-link-layer tunneling protocol with no encryption of its own.
L4 Load Balancing Load Balancing ☆ A method that distributes traffic based on IP address and port number.
L7 Load Balancing Load Balancing ☆ A method that distributes traffic by inspecting content such as URLs and HTTP headers.
Label Switching MPLS & Carrier Technology ☆ A method that forwards packets using a short label instead of an IP address.
LACP Switching ☆ A protocol that automatically bundles multiple physical links into a link aggregation.
LAN Cable Categories (Cat5e/Cat6) Optical & Physical Layer ☆ Standards that describe the performance of twisted-pair (LAN/Ethernet) cables, distinguished by a category number.
Latency QoS ☆ The delay time between sending data and receiving a response.
Layer 2 Switch Switching ☆ A switch that forwards frames based on MAC address.
Layer 3 Switch Switching ☆ A switch with routing capability, able to also handle IP addresses.
LDP MPLS & Carrier Technology ☆ A protocol that distributes MPLS label information between adjacent routers.
Least Connections Load Balancing ☆ A method that distributes to the server with the fewest connections at that moment.
Link Aggregation Switching ☆ A technology that bundles multiple physical links to treat them as a single, faster link.
Link Down Troubleshooting ☆ A state where a link is physically or logically disconnected.
Link-Local Address IPv6 Details ☆ An IPv6 address valid only within the same segment.
LLDP Network Management ☆ A protocol for exchanging information between neighboring devices regardless of vendor.
Load Balancer Load Balancing ☆ A device that distributes traffic across multiple servers to balance the load.
Local Preference BGP ☆ A BGP priority metric used when choosing a route from your own organization outward.
Longest Match Routing ☆ The principle of preferring the route with the longest matching prefix when multiple routes apply.
Loopback Address Routing ☆ A special address (such as 127.0.0.1) that refers to the device itself.
LSA Routing ☆ Advertisement information conveying link state, exchanged between routers in OSPF.
MAC Address Switching ☆ A unique 48-bit identifier assigned to a network device's physical interface.
MAC Address Table Switching ☆ A table a switch keeps to record the mapping between MAC addresses and ports.
MACsec Switching ☆ A Layer 2 encryption standard that encrypts Ethernet traffic on a per-frame basis.
MED Attribute BGP ☆ A metric that tells a neighboring AS which route it should preferably use to enter your network.
Mesh Wi-Fi Wireless LAN ☆ A wireless LAN configuration in which multiple access points cooperate to cover a wide area.
Metric Routing ☆ An evaluation value used to determine the priority of a route.
MIB Network Management ☆ A database defining the structure of information managed by SNMP.
Microburst QoS ☆ A momentary spike in traffic that doesn't show up in average bandwidth utilization.
MIMO Wireless LAN ☆ A technology that uses multiple antennas to send and receive multiple signals simultaneously.
MPLS MPLS & Carrier Technology ☆ A technology commonly used in carrier networks that uses labels to determine routes quickly.
MPLS VPN MPLS & Carrier Technology ☆ A service that uses an MPLS network to virtually connect multiple sites as if over a dedicated line.
MSS TCP/IP Basics ☆ The maximum size of the data portion TCP can send at once.
MSTP Switching ☆ A standard that groups multiple VLANs into instances to improve STP efficiency.
MTU TCP/IP Basics ☆ The maximum size of data that can be sent at once; anything larger is split.
MTU Mismatch Troubleshooting ☆ A problem where MTU settings differ along a path, causing packet fragmentation or drops.
Multicast TCP/IP Basics ☆ A communication method that sends to a specific set of multiple recipients simultaneously.
Multicast Group Address Multicast ☆ A special IP address range that serves as the destination for multicast communication.
Multi-Chassis Link Aggregation Data Center Networking ☆ A technology that forms link aggregation across different physical switches.
Multihop BGP BGP ☆ A configuration that establishes a BGP neighbor relationship with a peer that isn't directly connected.
Multi-Mode Fiber Optical & Physical Layer ☆ An optical fiber suited to short distances, at lower cost.
MU-MIMO Wireless LAN ☆ An advancement of MIMO that can send data to multiple devices simultaneously.
MX Record DNS ☆ A DNS record that specifies the server that receives mail addressed to a domain.
N+1 Redundancy Network Redundancy & Design ☆ A redundant configuration that provisions one more unit than the number required.
NAPT TCP/IP Basics ☆ A NAT method that shares a single global IP address among multiple devices using port numbers.
NAT TCP/IP Basics ☆ A technology that translates between private and global IP addresses.
NAT64 IPv6 Details ☆ A translation technology that allows access from an IPv6-only network to IPv4 resources.
Native VLAN Switching ☆ The default VLAN that passes through a trunk port without being tagged.
NDP IPv6 Details ☆ A protocol in IPv6, equivalent to ARP, that handles tasks such as MAC address resolution.
NetFlow Network Management ☆ A technology that collects statistical information about traffic flowing through a network.
Network Functions Virtualization (NFV) SD-WAN & SDN ☆ A technology for implementing functions like routers and firewalls as software on general-purpose servers instead of dedicated hardware.
Network Layer OSI Reference Model ☆ OSI layer 3, which handles route selection using IP addresses.
Network Loop Troubleshooting ☆ A state where wiring forms a closed path and packets keep circulating.
Network Segmentation Authentication & Access Control ☆ A design practice that divides a network into multiple segments to limit the spread of damage.
Network Tap Troubleshooting ☆ A dedicated device that copies out traffic flowing across a link without altering it.
Network Topology Network Management ☆ The physical or logical layout of how network devices are connected to each other.
NIC (Network Interface Card) Optical & Physical Layer ☆ The hardware used to connect a computer to a network.
North-South Traffic Data Center Networking ☆ Traffic that flows between clients outside a data center and the systems inside it.
NS Record DNS ☆ A DNS record indicating the name servers that manage a domain.
NTP Network Management ☆ A protocol that accurately synchronizes device clocks over a network.
OLT Access Network ☆ A PON termination device installed at the carrier's facility.
ONU Access Network ☆ A fiber termination device installed at the subscriber's premises.
OpenFlow SD-WAN & SDN ☆ A representative protocol used for communication between the controller and switches in SDN.
OSI Reference Model OSI Reference Model ☆ A model that organizes communication functions into seven layers.
OSPF Routing ☆ A link-state routing protocol commonly used within a single organization.
OSPFv3 Routing ☆ An extended version of OSPF that supports IPv6 networks.
Overlay Network Tunneling & Overlay ☆ A logically constructed virtual network built separately from the physical configuration.
Packet Capture Network Management ☆ Capturing and analyzing the packets flowing across a network.
Packet Loss QoS ☆ A phenomenon where a sent packet is lost along the way.
Path Attribute BGP ☆ An attribute attached to BGP route information that serves as material for route-selection decisions.
PDU OSI Reference Model ☆ A general term for the unit of data exchanged at each layer (frame, packet, etc.).
PE Router MPLS & Carrier Technology ☆ An MPLS router positioned at the edge of the carrier network, connecting to the customer network.
Physical Layer OSI Reference Model ☆ OSI layer 1, responsible for physical transmission over cables and electrical signals.
PIM Multicast ☆ A protocol used for multicast routing.
PIM-DM Multicast ☆ A dense-mode variant of PIM that first floods all paths, then prunes the unneeded ones.
PIM-SM Multicast ☆ A sparse-mode variant of PIM that builds only the paths that are needed.
Ping Network Management ☆ A command that uses ICMP to check connectivity with a remote host.
Ping Timeout Troubleshooting ☆ A state where no response arrives within a set time, causing the connectivity check to fail.
PMTUD TCP/IP Basics ☆ A mechanism that discovers the smallest MTU along a path to avoid packet fragmentation.
PoE Optical & Physical Layer ☆ A technology that supplies power over a LAN cable.
PoE+ Optical & Physical Layer ☆ An extension of PoE that increases the power that can be supplied.
Policy-Based Routing Routing ☆ A method that decides routing based on criteria such as source address, not just destination address.
PON Access Network ☆ A fiber access method that splits a single fiber to be shared among multiple subscribers.
Port Forwarding TCP/IP Basics ☆ A setting that forwards traffic addressed to a specific external port to a specific internal device.
Port Mirroring Troubleshooting ☆ A switch feature that copies traffic passing through a specific port and forwards it to another port.
Port Number TCP/IP Basics ☆ A number that identifies which application to communicate with within the same IP address.
Port Security Switching ☆ A security feature that allows communication on a port only from specific MAC addresses.
Port-Based Authentication Authentication & Access Control ☆ A mechanism that performs access control on a per-switch-port basis.
PPPoE Access Network ☆ A protocol that establishes a PPP connection over Ethernet to handle authentication and IP address assignment.
PPTP VPN ☆ A tunneling protocol commonly used in early VPNs; now deprecated due to security weaknesses.
Prefix List BGP ☆ A filter that permits or denies only specific prefixes.
Presentation Layer OSI Reference Model ☆ OSI layer 6, which handles data format conversion, encryption, and compression.
Private IP Address TCP/IP Basics ☆ An IP address used only within a limited scope such as inside an organization, not usable on the internet.
Private VLAN Switching ☆ A feature that further restricts port-to-port communication even within the same VLAN.
PTR Record DNS ☆ A DNS record used for reverse lookups, finding the domain name from an IP address.
PVST+ Switching ☆ A Cisco extension that runs a separate spanning tree instance per VLAN.
QoS QoS ☆ A mechanism that prioritizes traffic by type and controls bandwidth and delay.
QSFP Optical & Physical Layer ☆ A higher-capacity transceiver standard supporting faster communication than SFP.
Queuing QoS ☆ A mechanism that temporarily holds packets awaiting transmission.
QUIC TCP/IP Basics ☆ A next-generation, UDP-based transport protocol that underlies HTTP/3.
RA IPv6 Details ☆ An IPv6 message by which a router periodically advertises network information.
Radio Interference Wireless LAN ☆ A phenomenon where communication quality degrades because frequencies overlap with other radio signals.
RADIUS Authentication & Access Control ☆ A protocol that performs user authentication, authorization, and accounting.
Recursive Query DNS ☆ A method where a DNS server keeps querying on the client's behalf until it obtains the final answer.
Remote Access VPN VPN ☆ A VPN configuration that connects individual devices to an internal company network.
Rendezvous Point Multicast ☆ A router that serves as the relay point for multicast delivery in PIM-SM.
Repeater Optical & Physical Layer ☆ A device that amplifies and reshapes a signal to extend the reach of a cable.
Reverse Lookup DNS ☆ Looking up a domain name from an IP address.
Reverse Proxy Load Balancing ☆ A mechanism that sits between client and server, acting as the server's representative.
RIP Routing ☆ A long-established distance-vector routing protocol based on hop count.
Roaming Wireless LAN ☆ A feature that automatically switches the connected access point while a device is moving.
Root Bridge Switching ☆ The elected central switch that serves as the reference point for spanning tree calculations.
Root DNS Server DNS ☆ The topmost server in the DNS hierarchy.
Round Robin Load Balancing ☆ A method that allocates requests to servers evenly in turn.
Route Dampening BGP ☆ A mechanism that temporarily suppresses advertisement of an unstable route.
Route Map BGP ☆ A mechanism that conditionally changes attributes or filters route information.
Route Redistribution Routing ☆ Mutually importing route information between different routing protocols.
Route Reflector BGP ☆ A router that relays route information to simplify full-mesh iBGP connectivity.
Route Summarization Routing ☆ Consolidating multiple pieces of route information into one, simplifying the routing table.
Router Network Management ☆ A network-layer device that relays packets between different networks.
Routing Table Routing ☆ A table recording which route a packet should be sent over.
RSTP Switching ☆ A spanning tree protocol that speeds up STP, shortening convergence time.
SD-Branch SD-WAN & SDN ☆ An approach that centrally manages a branch site's networking functions together through software.
SDN SD-WAN & SDN ☆ An approach that centrally controls network devices through software.
SD-WAN SD-WAN & SDN ☆ A technology that centrally manages and optimally controls WAN links across multiple sites through software.
Sequence Number TCP/IP Basics ☆ A number used by TCP to manage the order of data sent.
Session Layer OSI Reference Model ☆ OSI layer 5, which manages the start, maintenance, and end of communication.
Session Persistence Load Balancing ☆ A mechanism that always routes traffic from the same user to the same server.
sFlow Network Management ☆ A technology that collects statistical information by sampling packets.
SFP Optical & Physical Layer ☆ A small optical/electrical transceiver standard fitted into network equipment.
Single Point of Failure Network Redundancy & Design ☆ A non-redundant point whose failure would halt the entire system.
Single-Mode Fiber Optical & Physical Layer ☆ An optical fiber with a thin core diameter, suited to long-distance transmission.
Site-to-Site VPN VPN ☆ A VPN configuration that keeps site-to-site networks permanently connected.
SLAAC IPv6 Details ☆ A mechanism by which a device automatically configures its own IPv6 address based on router advertisements.
SNMP Network Management ☆ A protocol for monitoring and managing the state of network devices.
SNMP Trap Network Management ☆ A mechanism by which a device proactively notifies a management server of an anomaly.
SOA Record DNS ☆ A DNS record indicating a zone's management information, such as its serial number and retry interval.
Socket TCP/IP Basics ☆ A communication endpoint formed by the combination of an IP address and port number.
Spanning Tree Protocol Switching ☆ A protocol that controls paths between switches to prevent loops from occurring.
Spanning Tree Reconvergence Troubleshooting ☆ The process by which STP recalculates a new path after a topology change.
Spine-Leaf Architecture Data Center Networking ☆ A two-tier network design used in data centers that makes latency easy to keep uniform.
SSID Wireless LAN ☆ A name used to identify a wireless LAN network.
SSL-VPN VPN ☆ A VPN method using SSL/TLS that allows easy connection from a browser and similar clients.
Standard ACL Authentication & Access Control ☆ A simple ACL that filters based only on source address.
Static NAT TCP/IP Basics ☆ A NAT method that permanently maps one private IP address to the same single global IP address.
Static Routing Routing ☆ A routing method where an administrator manually configures route information.
Subnet Mask TCP/IP Basics ☆ A value used to divide an IP address into a network portion and a host portion.
Subnetting TCP/IP Basics ☆ The process of dividing one network into multiple smaller networks (subnets).
Switch Stacking Switching ☆ A technology for connecting multiple physical switches so they can be treated as a single logical switch.
Syslog Network Management ☆ A mechanism for forwarding and aggregating device logs to an external server.
TACACS+ Authentication & Access Control ☆ An authentication protocol, common on Cisco devices, that also allows authorization at the command level.
TCP TCP/IP Basics ☆ A reliability-focused protocol that establishes a connection before communicating.
TCP Flags TCP/IP Basics ☆ Bits such as SYN, ACK, FIN, and RST that convey control information in a TCP segment.
TCP/IP Model OSI Reference Model ☆ A practically simplified four-layer model derived from the OSI reference model.
Three-Tier Network Architecture Data Center Networking ☆ The traditional model of designing switches in three layers — core, distribution, and access.
Three-Way Handshake TCP/IP Basics ☆ The three-step exchange -- SYN, SYN/ACK, ACK -- used to establish a TCP connection.
Throughput Measurement Troubleshooting ☆ Measuring the actual amount of data that can be transferred.
ToR Switch Data Center Networking ☆ A switch installed at the top of a rack that houses the servers.
Traceroute Network Management ☆ A command that discovers the route a packet takes to reach its destination.
Traffic Class QoS ☆ A group into which traffic is classified by type under QoS.
Traffic Policing QoS ☆ A control method that discards or restricts traffic exceeding a configured bandwidth.
Traffic Shaping QoS ☆ A technology that smooths transmission speed to suppress bursty load.
Transport Layer OSI Reference Model ☆ OSI layer 4, which uses port numbers to handle communication reliability and ordering.
Trunk Port Switching ☆ A port that carries traffic from multiple VLANs together over a single link.
TTL TCP/IP Basics ☆ A value indicating the maximum number of routers a packet can pass through; it's discarded when it reaches zero.
Tunneling VPN ☆ A technology that wraps data from one protocol inside another protocol for transport.
TXT Record DNS ☆ A DNS record that attaches arbitrary text information to a domain, used for things like SPF.
UDP TCP/IP Basics ☆ A protocol that prioritizes speed without establishing a connection.
Underlay Network Tunneling & Overlay ☆ The physical, real network that supports an overlay network.
Unicast TCP/IP Basics ☆ A one-to-one communication method.
Unique Local Address IPv6 Details ☆ An IPv6 address intended for use within an organization, not reaching the internet.
VLAN Switching ☆ A technology that logically divides a network without changing the physical wiring.
VPN VPN ☆ A technology that builds a virtual dedicated line over a public network such as the internet.
VRF MPLS & Carrier Technology ☆ A technology that lets a single router hold multiple independent routing tables.
VRRP Routing ☆ A protocol that makes a virtual default gateway redundant across multiple routers.
VTEP Tunneling & Overlay ☆ The endpoint that performs encapsulation and decapsulation in VXLAN.
VTP Switching ☆ A Cisco-proprietary protocol that automatically synchronizes VLAN information between multiple switches.
VXLAN Tunneling & Overlay ☆ An overlay technology that extends a layer 2 network over an IP network.
WDM Optical & Physical Layer ☆ A technology that increases capacity by sending multiple wavelengths of light through a single fiber.
Weight BGP ☆ A locally significant priority metric used for route selection on Cisco devices.
Weighted Round Robin Load Balancing ☆ A round-robin method that varies the distribution ratio according to each server's performance.
Well-Known Ports TCP/IP Basics ☆ Ports numbered 0-1023 whose use is predetermined, such as port 80 for HTTP.
WFQ QoS ☆ A queuing method that allocates bandwidth fairly across flows.
White Box Switch SD-WAN & SDN ☆ A switch built on generic hardware, not tied to a specific vendor.
Wi-Fi Wireless LAN ☆ A general term for the technology standards used to connect to a LAN wirelessly.
Wi-Fi 6 Wireless LAN ☆ The common name for 802.11ax, characterized by improved efficiency in high-density environments.
Wi-Fi 6E Wireless LAN ☆ A standard that extends Wi-Fi 6 technology into the 6GHz band.
Wi-Fi 7 Wireless LAN ☆ The common name for 802.11be, the latest standard aiming for even higher speed and lower latency.
Wildcard Mask TCP/IP Basics ☆ A masking notation, used in Cisco ACLs and similar configurations, whose bit meaning is the inverse of a subnet mask.
Window Size TCP/IP Basics ☆ A TCP value indicating how much data can be sent without waiting for acknowledgment.
Wireless LAN Controller Wireless LAN ☆ A device for centrally configuring and monitoring multiple access points.
WPA2 Wireless LAN ☆ An encryption and authentication standard for wireless LANs widely used before WPA3.
WPA3 Wireless LAN ☆ The current encryption and authentication standard for wireless LANs.
Zone Transfer DNS ☆ Replicating zone information from a primary DNS server to a secondary.
© 2026 ITBGM