Ccna Vocabulary

Front 1

Adjacent-Layer Interaction

Back 1

Two adjacent-layers in a networking architectural model work together with the lower layer providing services to the upper layer

Front 2

Same-Layer Interaction

Back 2

the communication between two networking devices for the purposes of the functions defined at a particular layer of a networking model, with that communication happening by using a header defined by that layer of the model. The two devices set values in the header, send the header and encapsulated data, w/ the receiving device(s) interpreting the header to decide what action to take.

Front 3

Leased Line

Back 3

A serial communications circuit between two points, provided by some service provider, typically a tele company. Telco charges a monthly fee

Front 4

WAN

Back 4

A part of a larger network that implements mostly OSI (L1) and (L2) technology, connects site that typically sit far apart and uses a business model in which a consumer (individual or business) must lease the WAN from an ISP

Front 5

Telco

Back 5

Common abbreviation for the telephone company

Front 6

Serial Interface

Back 6

A type of interface on a router, used to connect to some types of WAN links, particularly leased lines and Frame Relay Lines

Front 7

HDLC

Back 7

High-Level Data Link Control. A bit oriented synchronous data link layer protocol developed by the International Organization for Standardization (ISO)

Front 8

DSL

Back 8

Digital Subscriber Line. Public network technology that delivers high bandwidth over conventional telco-loop copper wiring at limited distances. Typically used an an Internet access technology, connecting a user to an ISP

Front 9

Cable Internet

Back 9

An Internet access technology that uses a cable TV cable, normally used for video, to send and receive data

Front 10

DSL modem

Back 10

A device that connects to a telephone line using DSL standards, to transmit and receive data to/from a telco using DSL

Front 11

Ethernet over MPLS

Back 11

Multi-Protocol Switching is a standards-approved technology for speeding up network traffic flow and making it easier to manage. Involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, saving time needed for a router to look up the address to the next node to forward the packet to .

Front 12

MPLS

Back 12

Multi-Protocol Switching is a multi-protocol that works w/ Internet Protocol (IP), Asynchronous Transport Protocol (ATM), and Frame Relay Protocols. Allows packets to be forwarded at the (L2) switching level rather than the (L3) routing level. Moves traffic faster and is easier to manage

Front 13

Wired LAN

Back 13

Local Area Network that physically transmits bits using cables (usually copper)

Front 14

Wireless LAN

Back 14

Local Area Network that physically transmits bits using radio waves.

Front 15

Unicast Address

Back 15

Any address in networking that represents a single device or interface, instead of a group of addresses

Front 16

Straight Through Cable

Back 16

A cable that connects the wire on pin 1 on one end of the cable w/ pin 1 on the other end of the cable, pin 2 on one end of the cable w/ pin 2 on the other end of the cable and so on

Front 17

RJ-45

Back 17

Type of cabling connector used for Ethernet cabling similar to RJ-11 connector used for telephone wiring. RJ-45 allows for the connection of 8 wires

Front 18

Network Interface Card (NIC)

Back 18

Computer card (expansion card or integrated into mobo) that provides the electronics and other functions to connect to a computer network.

Front 19

MAC Address

Back 19

Media Access Control Address, standardized data link layer address that is required for every device that connects to a LAN. Ethernet MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as hardware address, MAC layer address and a physical address

Front 20

Frame Check Sequence (FCS)

Back 20

Field in many data link trailers used as part of the error-detection process

Front 21

Gigabit Ethernet

Back 21

Common name for all the IEEE standards that send data at 1 gigabit speed per second

Front 22

Fast Ethernet

Back 22

Common name for all the IEEE standards that send data at 100 megabits speed per second

Front 23

Ethernet Frame

Back 23

Term referring to an Ethernet data link header and trailer, plus the data encapsulated between the header and trailer

Front 24

Ethernet Port

Back 24

A generic term for the opening on the side of any Ethernet node, typically in an Ethernet NIC or LAN switch, into which an Ethernet cable can be connected

Front 25

Ethernet Link

Back 25

A generic term for any physical link between two Ethernet nodes, not matter what type of cable is used.

Front 26

Ethernet Address

Back 26

A 48-bit (6-byte) binary number, usually written as a 12-digit hexadecimal number, used to identify Ethernet nodes in an Ethernet network. Ethernet frame headers list a destination and source address field, used by Ethernet devices to deliver Ethernet frames to the correct destination.

Front 27

Ethernet

Back 27

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

Front 28

IEEE

Back 28

Institute of Electrical and Electronics Engineers. Professional organization that develops communications and network standards

Front 29

Cross-over Cable

Back 29

Ethernet cable that swaps the pair used for transmission on one device to a pair used for receiving on the device on the opposite end.
10Base-T / 100Base-TX: swaps pins 1,2 to pins 3,6 and pins 3,6 to pins 1,2

Front 30

Broadcast Address

Back 30

Any address that represents all devices and can be used to send one message to all devices. In Ethernet, the MAC address = all 1s or FFFF.FFFF.FFFF.FFFF in hex.

Front 31

Default router

Back 31

On an IP Host, the IP address of some router to which the host sends packets when the packets destination address is on a subnet other than the local subnet

Front 32

Routing Table

Back 32

A list of routes in a router, with each route listing the destination subnet and mask, the router interface out which to forward packets destined to that subnet and as needed the next-hop router's IP address

Front 33

IP Network (Classful IP Network)

Back 33

An IPv4 Class A, B, or C network, called a classful network because these networks are defined by the class 4 rules for IPv4 addressing

Front 34

IP Subnet

Back 34

Subdivisions of Class A, B, or C network as configured by a network administrator. Subnets allow a single Class A, B or C network to be used instead of multiple networks and still allow for a large number of groups of IP addresses as is required for efficient routing

Front 35

IP Packet

Back 35

An IP Header followed by the data encapsulated after the IP header but specifically not including any headers and trailers for layers below the network layer

Front 36

Routing Protocol

Back 36

A set of messages and processes with which routers can exchange information about routes to reach subnets in a particular network. Examples: Enhanced Interior Gateway Routing Protocol, (EIGRP), Open Shortest Path First (OSPF), Routing Information Protocol (RIP)

Front 37

Dotted Decimal Notation

Back 37

The format used for IPv4 addresses in which four decimal values are used, separated by periods (dots)

Front 38

Connection Establishment

Back 38

The process by which a connection-oriented protocol creates a connection. With TCP, a connection is established by a three-way transmission of TCP segments

Front 39

Error Detection

Back 39

The process of discovering whether a data link level frame was changed during transmission. This process typically uses a Frame Check Sequence (FCS) field in the data link trailer.

Front 40

Error Recovery

Back 40

The process of noticing when some transmitted data was not successfully received and resending the data until is is successfully received

Front 41

Flow Control

Back 41

The process of regulating the amount of data sent by a sending computer toward a receiving computer. Several flow control mechanisms exist including TCP flow control, which uses windowing

Front 42

Forward Acknowledgement

Back 42

A process used by protocols that do error recovery in which the number that acknowledges data lists the next data that should be sent, not the last data that successfully received.

Front 43

HTTP

Back 43

Hyper Text Transfer Protocol, the protocol used by web browsers and web servers to transfer files such as text and graphic files

Front 44

Ordered Data Transfer

Back 44

A networking function included in TCP in which the protocol defines how the sending host should number the data transmitted transmitted, defines how the receiving device should attempt to reorder the data if it arrives out of order and specifies to discard the data if it cannot be delivered in order

Front 45

Port

Back 45

In TCP and UDP, a number that is used to uniquely identify the application process that either sent (source port) or should receive (destination port) data. In LAN switching another term for switch interface

Front 46

Segment

Back 46

In TCP, a term used to describe a TCP header and its encapsulated data (aka L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. In Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter how many cables are used)

Front 47

Sliding Windows

Back 47

For protocols such as TCP that allow the receiving device to dictate the amount of data the sender can send before receiving an acknowledgement -called a window-a reference to the fact that the mechanism to grant future windows is typically just a number that grows upward slowly after each acknowledgement, sliding upward

Front 48

URL

Back 48

Uniform Resource Locator, a standard for to refer to any piece of information retrievable via TCP/IP network, most notably used to identify web pages.

Front 49

VOIP

Back 49

Voice over IP, the transport of voice traffic inside IP packets over an IP network

Front 50

Web Server

Back 50

Software running on a computer that stores web pages and sends those web pages to web clients that request the web pages

Front 51

Auto-negotiation

Back 51

An IEEE standard mechanism (802.3u) with which two nodes can exchange messages for the purpose of choosing to use the same Ethernet standards on both ends of the link, ensuring that the link functions and functions w/out error

Front 52

Broadcast Domain

Back 52

A set of all devices that receive broadcast frames originating from any device w/in the set. Devices in the same VLAN are in the same broadcast domain

Front 53

Broadcast Frame

Back 53

An Ethernet frame sent to destination address FFFF.FFFF.FFFF.FFFF, meaning that frame should be delivered to all host on that LAN

Front 54

Collision Domain

Back 54

A set of network interface cards (NIC) for which a frame sent by one NIC could result in a collision w/ a frame sent by any other NIC in the same collision domain

Front 55

Cut-though Switching

Back 55

One of three options for internal processing on CISCO LAN switches in which the frame is forwarded as soon as enough of the Ethernet header has been received for the switch to make a forwarding decision including forwarding the first bit of the frame before the whole frame is received.

Front 56

Flooding

Back 56

The result of the LAN switch forwarding process for broadcast and unknown Unicast frames. Switches forward these frames out all interfaces except the interface on which the frame was received. Switches also flood multi-cast by default though that can be changed.

Front 57

Command Line Interface (CLI)

Back 57

An interface that allows the user to interact with the operating system by entering commands and optional arguments .

Front 58

Telnet

Back 58

The standard terminal emulation application layer protocol in the TCP/IP protocol stack. Used for remote terminal connection enabling users to log into remote systems and use local resources as if they were local. RFC 854

Front 59

Secure Shell (SSH)

Back 59

A TCP/IP application layer protocol that supports terminal emulation between client and server using dynamic key exchange and encryption to keep the communications private

Front 60

Enable Mode

Back 60

Part of the CISCO IOS CLI in which the user can use the most powerful and disruptive commands on a router or switch including the ability to reach configuration mode and reconfigure the router

Front 61

User Mode

Back 61

Mode of user interface to a router or switch in which the user can type only non-disruptive EXEC commands generally to look at the current status and not change any operational settings.

Front 62

Configuration Mode

Back 62

Part of CISCO IOS software CLI in which a user can type configuration commands that are then added to the device's current used configuration file running-config

Front 63

Start-Up Config File

Back 63

In CISCO IOS switches and routers the name of the file that resides in NVRAM memory holding the devices configuration that will be loaded into RAM as the running-config file when the device is next reloaded or restarted.

Front 64

Running-Config File

Back 64

In CISCO IOS switches and routers the name of the file that resides in RAM memory holding the devices currently used configuration

Front 65

802.1Q

Back 65

The IEEE Standardize protocol for VLAN trunking

Front 66

Trunk

Back 66

In campus LANs an Ethernet segment over which the devices add a VLAN header that identifies the VLAN in which the frame exists

Front 67

Trunk Interface

Back 67

A switch interface configured so that it operates using VLAN trunking (either 802.1Q or ISL)

Front 68

Trunking Administrative Mode

Back 68

The configured trunking setting on a CISCO switch interface, as configured with the switch port mode command

Front 69

Trunking Operational Mode

Back 69

The current behavior of CISCO switch interface for VLAN trunking

Front 70

VLAN

Back 70

A group of devices connected to one or more switches w/ the devices grouped into a single broadcast domain through switch configuration. Devices can be separated into separate VLANs w/out extra switches

Front 71

VTP

Back 71

VLAN trunking protocol = CISCO proprietary messaging protocol used btwn CISCO switches to communicate configuration information about the existence of VLANs including VLAN name and VLAN ID

Front 72

VTP Transparent Mode

Back 72

One of Three VTP operational modes Switches in transparent mode can configure VLANs but do not tell other switches about the changes and they do not learn about VLAN changes from other switches

Front 73

L3 Switch (aka Multilayer Switch)

Back 73

A LAN switch that can also perform L3 Routing Functions. Known as multilayer due to the device making forwarding decisions based on logic from multilayers L2 / L3

Front 74

Access Interface

Back 74

A LAN network design term that refers to a switch interface connected to end-user devices configured so that it does not use VLAN trunking

Front 75

CDP Neighbor

Back 75

A device on the other end of some communications cable that is advertising CDP updates

Front 76

Up and Up

Back 76

Refers to the two interface states on a CISCO router or switch (line status and protocol status). 1st Up refers to Line Status, 2nd Up refers to Protocol status.

Front 77

Connected

Back 77

The single-item status code listed by a switch show interface status command w/ this status referring to a working status

Front 78

Error Disabled

Back 78

An interface state on LAN switches that can be the result of many security violations

Front 79

Root Cause

Back 79

Troubleshooting term refers to the reason why a problem exists

Front 80

Subnet

Back 80

Subdivisions of a Class A, B or C network as configured. Subnets allow a Class A, B or C network to be used instead of multiple networks and still allow for a large number of IP addresses as is required for efficient IP routing

Front 81

Network

Back 81

A collection of computers, printers, switches, routers and other devices that can communicate w/ ea other across a transmission medium

Front 82

Classful Network

Back 82

An IPv4 Class A, B or C network called a classful network because these networks are defined by the class rules by IPv 4 addressing

Front 83

Variable Length Subnet Mask VLSM

Back 83

The capability to specify a different subnet mask for the same Class A, B or C network number on different subnets. VLSM can optimize available address space

Front 84

Network Part

Back 84

The portion of an IPv4 Address that is either 1,2 or 3 Octets/bytes long based on whether the address is in a Class A, B or C network

Front 85

Subnet Part

Back 85

In a subnetted IPv4 address interpreted with classful addressing rules one of the three parts of the structure of an IP address w/ the subnet part uniquely identifying different subnets of a classful IP network

Front 86

Host Part

Back 86

A term used to describe of an IPv4 address that is used to uniquely identify a host inside a subnet. The host part is identified by the bits of value 0 in the subnet mask

Front 87

Public IP Network

Back 87

An IP address that is part of a registered network number as assigned by the IANA member agency so that only the organization to which the address if registered is allowed to use the address Routers in the Internet should have routes allowing them to forward packets to all the publicly registered IP addresses

Front 88

Private IP Network

Back 88

IP Addresses in several Classful A, B or C networks that are set aside for use in private organizations. These addresses are not routable

Front 89

Subnet Mask

Back 89

A 32 bit number that numerically describes the format of an IP address by representing the combined network and subnet bits in the address w/ mask bit values of 1 and representing the host bits in the address w/ values of 0

Front 90

Default Mask

Back 90

The mask used in a Class A, B or C network that does not create any subnets.
255.0.0.0 Class A
255.255.0.0 Class B
255.255.255.0 Class C

Front 91

Resident Subnet

Back 91

The subnet of which an IP address is a member.

Front 92

Subnet Broadcast Address

Back 92

A special address in each subnet specifically the largest numeric address in the subnet designed so that packets sent to this address should be delivered to all host in that subnet

Front 93

Subnet Number

Back 93

In IPv4, a dotted decimal # that represents all addresses in a single subnet. Numerically the smallest value in the range of numbers in a subnet, reserved so that it cannot be used as a unicast IP address by a host

Front 94

IOS Image

Back 94

A file that contains the IOS

Front 95

Clock Rate

Back 95

The speed at which a serial link encodes bits on the transmission medium

Front 96

Bandwidth

Back 96

A reference to the speed of a networking link.

Front 97

ARP Table Address Resolution Table

Back 97

A list of IP addresses of neighbors on the same VLAN along w/ their MAC addresses as kept in memory by host and routers

Front 98

Routing Table

Back 98

A list of routes in a router w/ each route listing the destination subnet and mask, the router interface which to forward the packet out to that subnet and the next-hop routers IP address

Front 99

CISCO Express Forwarding (CEF)

Back 99

A method of internal processing on CISCO routers meant to make the routing process very efficient doing so by caching IP routes in a table that can be searched very quickly and by remembering data link headers rather than building them for every packet that is forwarded.

Front 100

Zero Subnet

Back 100

For every classful IPv4 network that is subnetted the one subnet that has all binary 0s in the subnet part of the number. In decimal the zero subnet can be easily identified because it is the same number as the classful network number

Front 101

IOS

Back 101

Internetwork Operating System: Software used on most CISCO routers and current CISCO network switches. IOS is a package of routing, switching, internetworking and telecommunicaitons integrated into a multitasking operating system

Front 102

17

Back 102

Define