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HOST/CLIENT

Describes the relationship between two computer programs in which one programs, the client, makes a service request from another program, the server, which fulfills the request.

APPLICATION SERVER

A software framework dedicated to the efficient execution of procedures (programs, routines, scripts) for supporting the construction of applications.

HUB

A common connection point for devices in a network.
- used to connect segments of a LAN
- operates at Layer 1 (Physical Layer) of the OSI model.

SWITCH

Capable of inspecting data packets as they are received, determining the source & destination device of each packet, & forwarding them appropriately
- conserves network bandwidth & offers better performance than a hub.
- Operates at Layer 2 (Data Link Layer) of the OSI model.

ROUTER

Reads the address information in the packet to determine its ultimate destination; then using information in its routing table/routing policy, it directs the packet to the next network on its journey or drops the packet.
- Operates at Layer 3 (Network Layer) of the OSI model because the wired/wireless router connects multiple networks (as gateways do)

PROXY SERVER

Acts as an intermediary for requests from clients seeking resources from other servers
- a client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server.

FIREWALL

Permit/deny network transmission to protect network from unauthorized access while permitting legitimate communications to pass.

VIRTUAL PRIVATE NETWORK (VPN) CONCENTRATOR

Device that incorporates the most advanced encryption & authentication techniques available; and are built specifically for creating a remote-access or site-to-site VPN and ideally are deployed where the requirement is for a single device to handle a very large number of VPN tunnels.

BACK-UP

Makes copies of data to restore the original after a data loss event.

NETWORK REPEATER

Preserve signal integrity & extend the distance over which data can safely travel

ACCESS

Small office/home office (SOHO) models, are located at customer sites such as branch offices that do not need hierarchical routing of their own.

DISTRIBUTION

Enforce quality of service across a WAN, so they may have considerable memory, multiple WAN interfaces, and substantial processing intelligence.

CORE

Provides a "collapsed backbone" interconnecting the distribution tier routers from multiple buildings of a campus, or large enterprise locations

Explain the Following Network Terminology:
BUS TOPOLOGY

Simplest way to connect multiple clients, but may have problems when two clients want to transmit at the same time on the same bus.
- Have some scheme of collisions handling/collision avoidance form communication on the bus, quite often using Carrier Sense Multiple Access or the presence of a bus master which controls access to the shared bus resource.

Explain the Following Network Terminology:
STAR TOPOLOGY

One central switch, hub or computer, which acts as a conduit to transmit messages.

Explain the Following Network Terminology:
RING TOPOLOGY

Each node connects to exactly 2 other nodes, forming a single continuous pathway for signals through each node
- Data travels from node to node, with each node along the way handling every packet.
- FDDI networks overcome this vulnerability by sending data on a clockwise & a counterclockwise ring; in the event of break

Explain the Following Network Terminology:
MESH TOPOLOGY

Each node in the network may act as an independent router
- component parts can all connect to each other via multiple hops, & they generally are not mobile.

Explain the Following Terminology:
LOCAL AREA NETWORK

Connected devices share the resources of a single processor/server within a small geographic area (for example, within an office building)

Explain the Following Terminology:
WIDE AREA NETWORK (WAN)

Spans a large geographic area, such as a state, province or country.

Explain the Following Terminology:
METROPOLITAN AREA NETWORK (MAN)

Large computer network that usually spans a city or a large campus

Explain the Following Terminology:
GLOBAL AREA NETWORK

Covers an unlimited geographical area.

Open Systems Interconnection (OSI)

A way of sub-dividing a communications system into smaller parts called layers.

OSI Layer 1

PHYSICAL
- Media, signal and binary transmission

OSI Layer 2

DATA LINK
- Physical addressing

OSI Layer 3

NETWORK
- Path determination & logical addressing

OSI Layer 4

TRANSPORT
- End-to-end connections & reliability, flow control

OSI Layer 5

SESSION
- Interhost communication

OSI Layer 6

PRESENTATION
- Data representation, encryption & decryption, convert machine dependent data to machine independent data.

OSI Layer 7

APPLICATION
- Network process to application

Transmission Control Protocol and Internet Protocol (TCP/IP)

Is the most used network protocol
- just one protocol, but a set of protocols (protocol stack)
- Protocol - language used to make 2 computers to talk to each other

Internet Protocol version 6 (IPv6)

Defined an IP address as a 128-bit number (consisting of 16 octets)

Unclassified but Sensitive Internet Protocol (IP) Router Network (NIPRNet)

A global long-haul IP based network to support unclass IP data communications services for combat support applications to the DoD, Joint Chiefs of Staff (JS), Military Departments (MILDEPS), and Combatant Commands (COCOM)

Secret IP Router Network (SIPRNet)

SECRET NOFORN

Joint Worldwide Intelligence Communications System (JWICS)

Operated by the DIA as a secure global network designed to meet the requirements for TS/SCI multimedia intelligence communications worldwide.

Department of Defense Network GIG

A globally interconnected, end-to-end set of information capabilities for collecting, processing, storing, disseminating, and managing information on demand to warfighters, policy makers, & support personnel.

Defense Information System Network (DISN)

The United States DoD's enterprise network for providing data, video & voice services.

Navy/Marine Corps Intranet (NMCI)

The major US-CONUS shore based Navy network providing SIPRNET & NIPRNET connectivity.

OCONUS Navy Enterprise Network (ONE-NET)

A Navy-wide initiative to install a common & secure IT infrastructure to OCONUS Navy locations to access NIPRNET & SIPRNET.
- designed to be interoperable with IT-21, NMCI, & GIG.

IT-21 Network

Network Connectivity capable of Voice, Data & Video for afloat units

Machine Language

A system of instructions & data executed directly by a computer's CPU.

Assembly Languages

A type of low-level language for programming computers, microprocessors, micro-controllers, & other integrated circuits. They implement a symbolic representation of the numeric machine codes & other constants needed to program a particular CPU architecture.

High-level Language

A programming language with strong abstraction from the details of the computer. It may use natural language elements, be easier to use or be more portable across platforms.
- Hides the details of CPU operations such as memory access models & management of scope.

Operating System:

A set of system software programs in a computer that regulate the ways application software programs use the computer hardware & the ways that users control the computer.

Applications

Computer software designed to help the user to perform singular or multiple related specific tasks.

Virus

Spreads from one computer to another (in some form of executable code) when its host is taken to the targeted infected computer.

Worms

Self-replicating malware computer programs.
They use a computer network to send copies of their selves to other nodes (computers on the network) and may do so without any user intervention.

Trojans

Malware that appears to perform a desirable function for the user prior to run or install but instead facilitates unauthorized access of the user's computer system.

Backdoor

Method of bypassing normal authentication, securing remote access to a computer, obtaining access to plaintext, and so on, while attempting to remain undetected.

Phishing

Acquire sensitive information by masquerading as a trustworthy entity in an electronic communication

Network Enumeration

Computing activity in which user names, and info on groups, shares and services of networked computers are retrieved.

Buffer Overflow

A program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory.

SQL injection

A code injection technique that exploits a security vulnerability occurring in the database layer of an application. The idea is to convince the application to run SQL code that was not intended.

Dictionary Attack

Technique for defeating a cipher or authentication mechanism by trying to determine its decryption key or passphrase by searching likely possibilities

Privilege Escalation

Gain access to resources which normally would have been protected from an application or user.

Brute Force Attack

Strategy used to break the encryption of data. It involves traversing the search space of possible keys until the correct key is found (trying to "crack" a password).

Social Engineering

More technical way of lying.

Public Key Infrastructure (PKI)

Arrangement that binds public keys with respective user identities by means of a certificate authority (CA).

Domain Name System (DNS)

Naming system for computers, services, or any resource connected to the Internet or a private network.
- Translates domain names (meaningful to humans) into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.

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