glossary 2 cis

Kernel

The portion of the operating system that interacts directly with computer hardware.

Shell

The portion of the operating system that interfaces with applications and the user.

Command-Line Interface (CLI)

A user interface to a computer operating system or application that depends on textual commands being entered by the user.

Graphical User Interface (GCI)

A user-friendly interface that uses graphical images and widgets, along with text, to indicate the information and actions available to a user when interacting with a computer.

Cisco Internetwork Operating System (IOS)

Generic term for the collection of network operating systems used by Cisco networking devices.

Firmware

Permanent software programmed into ROM memory.

Console

Term used to describe data transfer that requires the establishment of a virtual circuit.

Secure Shell (SSH)

A protocol that provides a secure remote connection to a host through a TCP application.

Telnet

A non-secure network service that supports CLI access to a remote host. It also can be used to verify the application later software between sources and destination stations.

User EXEC mode

The limited CLI mode where the commands available to the user area are a subset of those available at the privileged level. In general, use the user EXEC commands to temporarily change terminal settings, perform basic tests, and list system information.

Privileged EXEC Mode

An IOS administrative level mode that supports access to configuration.

Global Configuration Mode

A mode used to configure global parameters to enter other configuration submodes, such as interface, router, and line configuration submodes.

Ping

A troubleshooting tool used to verify network connectivity by sending a packet to a specific IP address and waiting for the reply.

Traceroute

A command on many computers operating systems that discovers the IP addresses and possible hostnames of the routers used by the network when sending a packet from one computer to another.

Virtual Terminal (VTY)

The text-based logical interface on an IOS device. It is accessed using Telnet or SSH to perform administrative tasks.

Nonvolatile Random-Access Memory (NV-RAM)

Memory whose contents are not erased when the computer is powered off.

Random-Access Memory (RAM)

Also known as read/write memory, which can have new data written to it and stored data read from it. It is no longer stored when power is removed from the device.

IPv4 Address

A 32-bit number, written in dotted decimal notation, used by the IPv4 protocol to identify an interface connected to an IP network uniquely.

Switch Virtual Interface (SVI)

A virtual interface for which there is no associated physical hardware on the device.

Dynamic Host Configuration Protocol (DHCP)

A protocol used to assign IP configurations to hosts dynamically. The services defined by the protocol are used to request and assign an IP address, a default gateway, and a DNS server address to a network host.

Domain Name System (DNS)

An internet-wide system by which a hierarchical set of DNS servers collectively hold all the name-to-IP address mapping and DNS servers refer users to the correct DNS server to successfully resolve a DNS name.