CCNA 200-301 Key Vocabulary Terms. Flashcards | Knowt

Adjacent-layer interaction

The topic of how on one computer, two adjacent layers in a network model work together, with the lower layer providing services to the higher layer.

De-encapsulation

The process where a receiving device interprets and removes lower-layer headers to reveal the next-higher-layer PDU.

Encapsulation

The placement of data from a higher layer protocol behind the header or in-between an Ethernet header and trailer.

Frame

A term referring to a data link header and trailer, plus the data encapsulated between them, sent on Layer 2 for OSI.

Packet

A logical grouping of bytes that includes the network layer header and encapsulated data.

PDU

Protocol Data Unit; a generic term referring to the header defined by a specific layer and its encapsulated data.

Same-layer interaction

The communication between two networking devices using headers defined by a particular layer to coordinate functions at that layer.

Segment

In TCP, an L4PDU consisting of a TCP header and data; in Ethernet, a single cable or collision domain.

Ethernet

A series of LAN standards defined by the IEEE, originally developed by Xerox, Intel, and Digital Equipment Corporation.

IEEE

Institute of Electrical and Electronics Engineers; a professional organization that develops communications and network standards.

NIC

Network Interface Card; a piece of hardware that allows a computer to connect to a network.

Straight-through cable

An Ethernet cable that connects the wire on pin 1 on one end to pin 1 on the other end, pin 2 to pin 2, and so on.

Crossover cable

A cable that swaps the transmission pair on one end to the receiving pair on the other end (pins 1,2 to 3,6).

MAC address

A 48-bit (6-byte) physical address required for every device on a LAN, controlled by the IEEE.

Unicast address

Any address in networking that represents a single device or interface.

Broadcast Address

An address representing all devices; in Ethernet, this is the MAC address FFFF.FFFF.FFFF.

Frame Check Sequence (FCS)

A field in many data link trailers used as part of the error-detection process.

Multimode Fiber (MMF)

Type of fiber-optic cable that uses LEDs and emits light at multiple angles.

Single-mode fiber (SMF)

Fiber-optic cable that allows only a single light wave to pass down the cable.

Leased line

A serial communications circuit between two points provided by a service provider, typically a telco.

HDLC

High-level Data Link Control; a bit-oriented synchronous data link layer protocol developed by ISO.

Default gateway

The IP address of a router to which a host sends packets when the destination is on a different subnet.

Routing table

A list in a router containing destination subnets, masks, outgoing interfaces, and next-hop IP addresses.

ARP

Address Resolution Protocol; used to map a known IP address to a MAC address.

Spanning Tree Protocol (STP)

A protocol (802.1D) that prevents Layer 2 loops by dynamically blocking certain switch ports.