Packet

In data communications, the basic logical unit of information transferred. A packet consists of a certain number of data bytes, wrapped or encapsulated in headers and/or trailers that contain information about where the packet came from, where it is going, and so on. The various protocols involved in sending a transmission add their own layers of header information, which the corresponding protocols in receiving devices then interpret.

Packets

A unit of information transmitted as a whole from one device to another on a network.

Packet Filter

A static filter used to specify the type of IP traffic that is either specifically allowed or denied into or out of your network. These filters can evaluate packets based upon protocol (TCP, UDP, ICMP), port number, destination address, or source address.

Packet Level Protocol (PLP)

Occasionally called X.25 Level 3 or X.25 Protocol, a Network-layer protocol that is part of the X.25 stack.

Packet Switch

A physical device that makes it possible for a communication channel to share several connections, its functions include finding the most efficient transmission path for packets.

Packet Switch Exchange (PSE)

The X.25 term for a switch.

Packet-Switched Network (PSN)

Any network that uses packet-switching technology. Also known as packet-switched data network
(PSDN). See also Packet Switching.

Packet Switching

A networking technology based on the transmission of data in packets. Dividing a continuous stream of data into small units – packets – enables data from multiple devices on a network to share the same communication channel simultaneously but also requires the use of precise routing information.

Page

The smallest unit of data storage in SQL Server. Every page is 8KB in size with a 96-byte header. Data rows are written to data pages, index rows to index pages, and so on.

Page File

Logical memory that exists on the hard drive. If a system is experiencing excessive paging (swapping between the page file and physical RAM), it needs more memory. See
Swap File.

PAP

See Password Authentication Protocol.

Parallel Interface

A device that allows transfer of blocks of data in bytes.

Parallel Striped Backup

A SQL Server backup created across two or more backup devices.

Parameter

Additional information appended to an MS-DOS command to indicate how the command should be executed.

Parent Domain

A relative term that describes a domain that is a parent of another domain. Parent domains may contain child domains (also called subdomains).

Parity Checking

A simple form of error checking employed by asynchronous modems. Extra bits added to data words can indicate when data transmission has been flawed.

Partial Mesh

A type of network topology in which some network nodes form a full mesh (where every node has either a physical or a virtual circuit linking it to every other network node), but others are attached to only one or two nodes in the network. A typical use of partial-mesh topology is in peripheral networks linked to a fully meshed backbone. See also Full Mesh.

Partition

A section of a hard disk that can contain an independent file system volume. Partitions can be used to keep multiple operating systems and file systems on the same hard disk. See also Volume and Hard Disk Drive.

Passive Hub

A hub that simply combines the signals of network segments, with no signal processing or regeneration.

Passthrough Action

A security filter action, this “Permit” action tells the IPSec filter to take no action. It neither accepts nor rejects the connection based on security rules, meaning that it adds zero security. It allows traffic to pass without modification.

Password

A secret code used to validate the identity of a user of a secure system. Passwords are used in tandem with account names to log on to most computer systems.

Password Attacks

A password attack is an attempt to obtain or decrypt a legitimate user’s password. Hackers can use password dictionaries, cracking programs, and password sniffers in password attacks. Defense against password attacks is rather limited but usually consists of a password policy including a minimum length, unrecognizable words, and frequent changes. See also Password Sniffing.

Password Authentication Protocol (PAP)

In Point-to-Point Protocol (PPP) networks, a method of validating connection requests. The requesting (remote) device must send an authentication request, containing a password and ID, to the local router when attempting to connect. Unlike the more secure CHAP (Challenge Handshake Authentication Protocol), PAP sends the password unencrypted and does not attempt to verify whether the user is authorized to access the requested resource; it merely identifies the remote end. See also Challenge-Handshake Authentication Protocol.

Password Policies

Windows 2000 policies used to enforce security requirements on the computer. Password policies are set on a per-computer basis, and they cannot be configured for specific users. Password policies are set through account policies. See also Account Policies.

Password-Protected Shares

A network security model in which passwords are required for gaining access to each shared resource on a network.

Password Sniffing

The use of a sniffer to capture passwords as they cross a network. The network could be a local area network, or the Internet itself. The sniffer can be hardware or software. Most sniffers are passive and only log passwords. The attacker must then analyze the logs later. See also Sniffer.

PASV Mode

A connection mode of the FTP protocol that arbitrarily chooses the data port for packet transfer.

Patch

A Windows Installer file that updates application code. Patches can be used to ensure that new features are installed after an application has already completed installation.

PATH

Displays or sets a search path for executable files.

Pathworks

A version of LAN Manager for DEC computer systems running the VMS operating system and DEC Unix. See also Network Operating System.

PAUSE

Suspends processing of a batch file and displays a message.

Payload

1. The data to be transmitted to the remote computer.
2. Refers to the effects produced by a virus attack. Sometimes refers to a virus associated with a dropper or Trojan horse.

PB

See Petabyte.

PC

See Personal Computer.

PC Card

A special, credit-card-sized device used to add devices to a laptop computer. Also called a PCMCIA card.

PC-DOS

IBM’s implementation of DOS for IBM PCs first introduced in 1981.

PCI

See Peripheral Connection Interface.

PCMCIA Card

See Personal Computer Memory Card International Association Card.

PC Memory Card International Association

A nonprofit association, formed in 1989, with more than 320 members in the computer and electronics industries, that developed a standard for credit card-sized, plug-in adapters designed for portable computers.

PCR

See Peak Cell Rate.

PCX

A standard file format used for bitmapped graphics.

PDC

See Primary Domain Controller.

PDN

See Public Data Network.

PDU

See Protocol Data Unit.

Peak Cell Rate (PCR)

In Asynchronous Transfer Mode (ATM), the maximum cell rate that a specific data source on the network can sustain. See also Asynchronous Transfer Mode, Available Cell Rate, Minimum Cell Rate, and Sustainable Cell Rate.

Peer

A networked computer that both shares resources with other computers and accesses the shared resources of other computers. A nondedicated server. See also Server and Client.

Peer Filters

Filters that give you control over which neighboring routers your router will listen to; use the RRAS snap-in to configure peer filters and route filters.

Peer-to-Peer Communication

A networked computer that both shares resources with other computers and accesses the shared resources of other computers.

Peer-to-Peer Network

A local area network in which network resources are shared among workstations, without a file server.

Peer Web Services (PWS)

Software that acts as a small-scale Web server, for use with a small intranet or a small Internet site with limited traffic. Windows 2000 uses PWS to publish resources on the Internet or a private intranet. When you install Internet Information Services (IIS) on a Windows 2000 Professional computer, you are actually installing PWS.

Pentium

The fifth generation of the Intel family of microprocessors upon which PC-compatible computers are based. The Pentium includes advanced microprocessor features like parallel pipeline, out-of-order execution, large on-chip caches, built-in support for multiprocessing, and extremely fast floating point math performance.

Pentium Pro

The sixth generation of the Intel family of microprocessors, the Pentium Pro is actually a RISC microprocessor that translates Pentium op codes into multiple RISC instructions for execution. This architecture allows the Pentium Pro to take advantage of advancements in microprocessor design more efficiently than complex instruction set computers (CISC) like the Pentium can. See also Reduced Instruction Set Computer.

Performance Counter

A data item that is associated with a system object. It measures a particular aspect of that object’s performance. Examples include the Pages per Second counter of the Memory object or the % Processor Time counter of the Processor object.

Performance Log

Windows performance information that is stored to a file within the file system for later analysis or for analysis using other applications.

Performance Logs and Alerts

A Windows utility used to log performance-related data and generate alerts based on performance-related data.

Performance Monitor

A Windows program that lets you monitor important system parameters for the computers on your network in real time. Performance Monitor can keep an eye on a large number of system parameters, providing a graphical or tabular profile of system and network trends.

Performance Object

The particular system object or service, such as memory, processor, or web service, that you wish to monitor.

Perimeter Network

A small, secured network that contains resources you wish to make available to external users. Secured from the outside by a firewall or other means, it is also separated from the rest of the internal, private network as well.

Periodic Update Mode

RIP update mode in which routing table updates are automatically sent to all other RIP routers on the internetwork. See also Auto-Static Update Mode.

Peripheral

An input/output device attached to a computer. Peripherals can be printers, hard disk drives, monitors, and so on.

Peripheral Connection Interface (PCI)

A high speed 32/64-bit bus interface developed by Intel and widely accepted as the successor to the 16-bit ISA interface. PCI devices support I/O throughput about 40 times faster than the ISA bus.

Permanent Virtual Circuit (PVC)

A permanent route through the network that is always available to the customer. With a PVC, charges are still billed on a per-use basis.

Permanent Virtual Path (PVP)

A virtual path made up of PVCs. See also Permanent Virtual Circuit.

Permissions

Security constructs used to regulate access to resources by user name or group affiliation. Permissions can be assigned by administrators to allow any level of access, such as read only, read/write, delete, by controlling the ability of users to initiate object services. Security is implemented by checking the user’s security identifier against each object’s access control list. See also Security Identifiers and Access Control List.

Permuted Index

A special kind of index used in several of the Unix system manuals. Many of the Unix manuals treat each command on a separate page, and these pages are not numbered continuously; they are numbered only within each command. This makes it easy to add or remove pages as requirements change, but it can make it difficult to find specific information. The permuted index is the solution. The permuted index has three columns. The central column, where you start your search, is in alphabetic order. The column to the right lists the command that performs the function and the section number in the man pages where you will find a detailed description, and the column on the left contains additional keywords to help confirm that you have found the correct entry. See also Man Pages.

Per-Seat License

A type of SQL Server license that allows you to pay once for each seat (person) in your company, and then use any number of connections to any number of SQL servers.

Per-Server License

A type of SQL Server license that allows you to pay for only a connection to a single server.

Personal Address Book (PAB)

An address book created by a user and stored on that user’s computer or a server.

Personal Computer (PC)

A microcomputer used by one person at a time (i.e., not a multiuser computer). PCs are generally clients or peers in a networked environment. High-speed PCs are called workstations. Networks of PCs are called LANs. The term PC is often used to refer to computers compatible with the IBM PC.

Personal Computer Memory Card International Association (PCMCIA) Card

A special, credit-card-sized device used to add devices to a laptop computer. Also called a PC Card.

Personal Storage Folder (PST)

Folders created by a user and used for message storage instead of using their mailbox in the Private Information Store. PSTs can be located on a user’s computer or on a server.

Personal Web Manager

A Windows 2000 utility used to configure and manage Peer Web Services (PWS). This utility has options for configuring the location of the home page and stopping the Web site, and displays statistics for monitoring the Web site. See also Peer Web Services (PWS).

Petabyte

A computer storage measurement that is equal to 1,024 terabytes.

PGP

See Pretty Good Privacy.

Phase

The amplitude of a cyclic signal at a specific point in time.

Physical I/O

See I/O.

Physical Layer

The lowest layer – Layer 1 – in the OSI reference model, it is responsible for converting data packets from the Data Link layer (Layer 2) into electrical signals. Physical layer protocols and standards define, for example, the type of cable and connectors to be used, including their pin assignments and the encoding scheme for signaling 0 and 1 values. See also Application Layer, Data Link Layer, Network Layer, Presentation Layer, Session Layer, and Transport Layer.

Physical Port

Printers can be connected directly to a computer through a serial (COM) or parallel (LPT) port. If a printer is connected in this manner, it is using a physical port. See also Printers and Print Device.

Physical Topology

Describes the actual layout of the network transmission media.

Piggyback

To gain unauthorized access to a system via an authorized user’s legitimate connection.

Ping (Packet Internet Groper)

A packet used to test reachability of destinations by sending them an ICMP echo request and waiting for a reply. The term is used as a verb: “Ping host A to see if it is up”.

PING

A command used to send an Internet Control Message Protocol (ICMP) echo request and echo reply to verify that a remote computer is available.

Pixel

A picture element on screen; the smallest element that can be independently assigned color and intensity.

PKUNZIP

A very popular file decompression utility available as shareware. PKUNZIP uncompresses files or archives created by PKZIP; both programs are usually available together. See also PKZIP and WinZip.

PKZIP

A very popular file compression utility available as shareware. PKZIP not only compresses files to save disk space or cut modem transmission times, but also combines compressed files to create compressed archives. See also strong>PKUNZIP and WinZip.

Plaintext

Unencrypted data. Synonymous with cleartext.

Plant

The wires that connect computers together in a LAN.

Pleisochronous

Nearly synchronous, except that clocking comes from an outside source instead of being embedded within the signal as in synchronous transmissions.

Plenum

The space between the ceiling of an office and the floor above. Usually, fire codes require that only special, plenum-grade cable be used in this space.

Plotters

Print devices that use a numeric-control stylus to draw on paper rather than the raster print process employed by laser and ink-jet printers. Plotters are typically used to produce large, high-resolution line art such as blueprints.

PLP

See Packet Level Protocol.

Plug and Play

A technology that uses a combination of hardware and software to allow the operating system to automatically recognize and configure new hardware without any user intervention.

PNNI

See Private Network-Network Interface.

Pointer Record (PTR)

Associates an IP address to a host name.

Point of Presence (POP)

The physical location where an interexchange carrier has placed equipment to interconnect with a local exchange carrier.

Point-to-Multipoint Connection

In ATM, a communication path going only one way, connecting a single system at the starting point, called the “root node”, to systems at multiple points of destination, called “leaves”. See also Point-to-Point Connection.

Point-to-Point

Network communication in which two devices have exclusive access to a network medium. For example, a printer connected to only one workstation would be using a point-to-point connection.

Point-to-Point Connection

In ATM, a channel of communication that can be directed either one way or two ways between two ATM end systems. See also Point-to-Multipoint Connection.

Point-to-Point Protocol (PPP)

A Network layer transport that performs over point-to-point network connections such as serial or modem lines. PPP can negotiate any transport protocol used by both systems involved in the link and can automatically assign IP, DNS, and gateway addresses when used with TCP/IP. See also Internet Protocol, Domain Name Service and Gateway.

Point-to-Point Tunneling Protocol (PPTP)

Protocol used to create secure connections between private networks through the public Internet or an ISP. See also Internet and Internet Service Provider.

Poison-Reverse Processing

An option that, when enabled, specifies that routes learned from a network are rebroadcast to the network with a metric of 16, a special value that tells other routers that the route is unreachable. This also prevents routing loops while still keeping the routing tables up to date.

Poison Reverse Updates

These update messages are transmitted by a router back to the originator (thus ignoring the split-horizon rule) after route poisoning has occurred. Typically used with DV routing protocols in order to overcome large routing loops and offer explicit information when a subnet or network is not accessible (instead of merely suggesting that the network is unreachable by not including it in updates). See also Route Poisoning.

Policies

General controls that enhance the security of an operating environment. In Windows, policies affect restrictions on password use and rights assignment and determine which events will be recorded in the Security log.

Policy

A collection of configuration settings that can be applied to objects of the same class in Active Directory. In relation to Exchange, this may include mailbox thresholds and deleted item retention.

Policy Inheritance

Each policy that is processed will override those settings made in policies applied earlier in the process. In other words, if a parameter is set to “true” in the local policy, the site policy could change it to “false”, the domain policy could change it back to “true”, and then various OU policies could change it back.

Policy Mode

The module that contains information about how the CA handles an incoming request.

Polling

One device is responsible for polling the other devices to see if they are ready for the transmission or reception of data.

Polymorphic Virus

Polymorphic viruses create varied (though fully functional) copies of themselves as a way to avoid detection from anti-virus software. Some polymorphic viruses use different encryption schemes and require different decryption routines. Thus, the same virus may look completely different on different systems or even within different files. Other polymorphic viruses vary instruction sequences and use false commands in the attempt to thwart anti-virus software. One of the most advanced polymorphic viruses uses a mutation-engine and random-number generators to change the virus code and its decryption routine. See also Mutating Virus.

POP

See Point of Presence and Post Office Protocol 3.

POP3

See Post Office Protocol 3.

Port

An input/output address through which your PC interacts with external devices.

Portable Computer

Any computer light and small enough to be carried easily. There are two types: laptop computers and notebook computers. Major advances in battery life and the use of flash memory are part of the continuing development of portable computers. See also Docking Station and Port Replicator.

Portable Open Systems Interconnect (POSIX)

A set of standards used to ensure cross-platform compatibility of client/server applications.

Port Number

A numeric identifier assigned to an application. Transport protocols like TCP use the port number to identify to which application to deliver a packet.

Port Replicator

A device containing standard computer ports used to avoid constantly connecting and disconnecting peripherals from a portable computer. A port replicator duplicates all your computer’s ports and even may add a Small Computer System Interface (SCSI) port or a second Universal Serial Bus port. The external monitor, full-sized keyboard, and mouse you use in the office are connected to the port replicator; when it is time to take the portable computer on the road, you simply unplug the port replicator, leaving everything attached to the replicator for your return. See also Docking Station.

Port Security

Used with Layer-2 switches to provide some security. Not typically used in production because it is difficult to manage. Allows only certain frames to traverse administrator-assigned segments.

POST

See Power On Self Test.

Post Form

A form used to send information directly to a folder without using messaging routing.

Post Office Protocol 3 (POP3)

A standards-based protocol for simple access to Inbox data. All versions of Exchange Server except version 4.0 support POP3. POP3 uses TCP/IP port 110 for client to server access.

Postoffice

An MS Mail server that stores messages.

Post Upgrade Method

A method of upgrading to Windows 2000 in which existing NT domain controllers are upgraded first and any modifications to the domain structure are implemented afterward.

Potential Browser

A computer on a network that may maintain a list of other computers and services on the network if requested to do so by a Master browser. See also Browser and Master Browser.

POWER

Turns power management on and off.

Power On Self Test (POST)

A part of the Windows boot sequence. The POST detects a computer’s processor, how much memory is present, what hardware is recognized, and whether or not the BIOS is standard or has Plug-and-Play capabilities.

PowerPC

A microprocessor family developed by IBM to compete with the Intel family of microprocessors. The PowerPC is a RISC-architecture microprocessor with many advanced features that emulate other microprocessors. PowerPCs are currently used in a line of IBM computers and in the Apple Power Macintosh. Windows NT is available for the PowerPC.

Power Users Group

A Windows built-in group that has fewer rights than the Administrators group, but more rights than the Users group. Members of the Power Users group can perform tasks such as creating local users and groups and modifying the users and groups that they have created.

PPP

See Point-to-Point Protocol.

PPTP

See Point-to-Point Tunneling Protocol.

Pre-Boot Execution Environment (PXE)

A technology that allows a client computer to remotely boot and connect to a Remote Installation Service (RIS) server. See also Remote Installation Service (RIS).

Preemptive Multitasking

A multitasking implementation in which an interrupt routine in the Kernel manages the scheduling of processor time among running threads. The threads themselves do not need to support multitasking in any way because the microprocessor will preempt the thread with an interrupt, save its state, update all thread priorities according to its scheduling algorithm, and pass control to the highest priority thread awaiting execution. Because of the preemptive nature, a thread that crashes will not affect the operation of other executing threads. See also Kernel, Thread, Operating System, and Process.

Preferences

Characteristics of user accounts, such as password, profile location, home directory, and logon script.

Presentation Layer

Layer 6 of the OSI reference model, it defines how data is formatted, presented, encoded, and converted for use by software at the Application layer. See also Application Layer, Data Link Layer, Network Layer, Physical Layer, Session Layer, and Transport Layer.

Prestaging

The process of identifying computers that are to be installed through the use of Remote Installation Services. Prestaging can increase security by only allowing specific machines to perform a remote installation. See also Remote Installation Services (RIS).

Pretty Good Privacy (PGP)

A popular public-key/private-key encryption application offering protected transfer of files and messages.

PRI

See Primary Rate Interface.

Primary DNS Server

A primary DNS server is the “owner” of the zone files defined in its database. The primary DNS server has authority to make changes to the zone files it owns.

Primary DNS Suffix

Automatically appended upon DNS requests if the Append Primary And Connection Specific DNS Suffixes radio button is selected on the DNS tab of the Advanced TCP/IP Settings dialog box.

Primary Domain Controller (PDC)

Primary and Backup Domain Controllers perform essentially the same function. It is their role to store the user account database. The difference is that a PDC stores the master copy of this database. It is on this master copy that changes can occur. When a new user is added, the PDC’s database is affected. See also Backup Domain Controller, Domain and Master Browser.

Primary Domain Controller (PDC) Emulator

A Windows 2000 domain controller that is used primarily for backwards compatibility with Windows NT domain controllers.

Primary Partition

A part of basic storage on a disk. The primary partition is the first partition created on a hard drive. The primary partition uses all of the space that is allocated to the partition. This partition is usually marked as active and is the partition that is used to boot the computer. See also Basic Storage and Boot.

Primary Rate

Primary Rate supports twenty-three 64 Kbps B channels and one 64 Kbps D channel. The D channel is used for signaling and management, and the B channels provide the data throughput.

Primary Rate Interface

A type of ISDN connection between a PBX and a long-distance carrier, which is made up of a single 64Kbps D channel in addition to 23 (T1) or 30 (E1) B channels. See also Integrated Services Digital Network.

Primary Rate ISDN

Abbreviated PRI. An ISDN (Integrated Services Digital Network) service that provides 23 B (bearer) channels, capable of speeds of 64Kbps, and one D (data) channel, also capable of 64Kbps. The combined capacity of 1.544 Mbps is equivalent to one T1 channel. See also Basic Rate ISDN.

PRINT

Prints a text file while you are using other MS-DOS commands.

Print Device

A physical device that produces printed output. See also Printers.

Print Driver

The software component that interfaces the print device to the operating system. See also Print Device.

Printer Object

An Active Directory object that identifies printers that are published within domains.

Printers

Peripheral devices that produce paper copy of computer data. See also Laser Printers, Ink-Jet Printers, Plotters, and Peripheral.

Printing Pool

A number of print devices controlled by the same printer. The printer directs the print job to an available print device in the pool. See also Printers and Print Device.

Printing Services

Services that allow the sharing of a printer.

Print Processor

Once a print job has been sent to the spooler, the print processor looks at the print job and determines whether or not the job needs further processing. The processing (also called rendering) is used to format the print job so that it can print correctly at the print device. See also Print Spooler.

Print Queue

The list of print jobs waiting to be sent to a printer. See also Print Spooler.

Print Server

A computer to which printers are attached and connected via the network. See also Printers and Print Device.

Print Spooler

The print spooler is a directory or folder on the Print Server that actually stores the print jobs until they can be printed. It’s very important that your Print Server and Print Spooler have enough hard disk space to hold all of the print jobs that could be pending at any given time. See also Print Server.

Priority

A level of execution importance assigned to a thread. In combination with other factors, the priority level determines how often that thread will get computer time according to a scheduling algorithm. See also Preemptive Multitasking.

Priority Queueing

A routing function in which frames temporarily placed in an interface output queue are assigned priorities based on traits such as packet size or type of interface.

Pristine Installation Method

A method of upgrading to Windows 2000 in which a new Windows 2000 domain controller is installed and configured (including Active Directory) and the business is moved to this environment after it is set up.

Private Addresses

These addresses cannot receive traffic from, or send traffic to, the Internet. In every other respect, though, they are just ordinary IP addresses. The idea behind private addresses is that you can use them to configure a network that is not connected to the Internet. If you wish to connect these machines to the Internet, you can use NAT to translate between public and private addresses.

Private Folder

A server-based folder that is part of a user’s mailbox. Private folders are stored on an Exchange server in the private information store. The Inbox and Outbox are examples of private folders.

Private Key

The half of a key pair that is known only by one user and is used to decrypt data and to digitally sign messages.

Private Network-Network Interface (PNNI)

An ATM Forum specification for offering topology data used for the calculation of paths through the network, among switches and groups of switches. It is based on well-known link-state routing procedures and allows for automatic configuration in networks whose addressing scheme is determined by the topology.

Procedure Cache

After SQL Server fulfills its requirements for RAM from the RAM assigned to it, the rest is assigned to cache. The cache is divided into a data cache and a procedure cache. The procedure cache contains stored procedures that have been run by users or the system. The ratio of procedure cache to data cache is now set automatically by SQL Server.

Process

A running program containing one or more threads. A process encapsulates the protected memory and environment for its threads.

Process/Application Layer

The upper layer in the DoD model that refers to the Application, Presentation, and Session layers of the OSI model.

Processor

A circuit designed to automatically perform lists of logical and arithmetic operations. Unlike microprocessors, processors may be designed from discrete components rather than be a monolithic integrated circuit. See also Microprocessor.

Processor Affinity

The association of a processor with specific processes that are running on the computer. Processor affinity is used to configure multiple processors.

Process Switching

As a packet arrives on a router to be forwarded, it is copied to the router’s process buffer, and the router performs a lookup on the Layer 3 address. Using the route table, an exit interface is associated with the destination address. The processor forwards the packet with the added new information to the exit interface, while the router initializes the fast-switching cache. Subsequent packets bound for the same destination address follow the same path as the first packet.

Process Throttling

A method for limiting the percentage of CPU processing that can be used by a Web site.

Product/Service-Based Model

A business model in which resources are dedicated to the support of whatever products or services the company sells.

Professional Office System (PROFS)

An International Business Machine (IBM) host-based messaging application.

Program

A list of processor instructions designed to perform a certain function. A running program is called a process. A package of one or more programs and attendant data designed to meet a certain application is called software. See also Software, Application, Process, and Microprocessor.

Program Developers’ Kit (PDK)

Extra SQL Server documentation and programming examples useful to developers who wish to know which DLL (dynamic link library) functions are available and how they work in SQL Server.

Program Infector

A program infector virus infects other program files once an infected application is executed and the activated virus is loaded into memory.

Programmable Read-Only Memory (PROM)

ROM that is programmable only once, using special equipment. See also Electronically Erasable Programmable Read-Only Memory and Erasable Programmable Read-Only Memory.

Programming Interfaces

Interprocess communications mechanisms that provide certain high-level services to running processes. Programming interfaces may provide network communication, graphical presentation, or any other type of software service. See also Interprocess Communications.

PROM

See Programmable Read-Only Memory.

Promotion

The act of converting a Windows Server computer to a domain controller. See also Active Directory Installation Wizard.

PROMPT

Changes the MS-DOS command prompt.

Prompt

The System prompt displayed on a screen, such as A:\ or C:\, indicating that DOS is ready to accept commands.

Propagation Dampening

An algorithm used to prevent unnecessary replication of directory changes.

Propagation Delay

The time it takes data to traverse a network from its source to its destination.

Property

A characteristic of an object. Properties of a mailbox include display name, primary Windows account, and storage limits. The terms property and attribute are synonymous.

Proprietary

Describes a system that is defined by one vendor and typically not supported by others. ARCnet started as a proprietary protocol, as did Token Ring.

Protected Mode

The operating mode of 286 (and higher) processors, not normally used by DOS. It allows more than 1 MB of memory to be addressed.

Protocol

An established communication method that the parties involved understand. Protocols provide a context in which to interpret communicated information. Computer protocols are rules used by communicating devices and software services to format data in a way that all participants understand. See also Transport Protocol.

Protocol Analyzers

Hardware or software products that are used to monitor network traffic, track network performance, and analyze packets. Protocol analyzers can identify bottlenecks, protocol problems, and malfunctioning network components.

Protocol Data Unit (PDU)

Is the name of the processes at each layer of the OSI model. PDUs at the Transport layer are called segments; PDUs at the Network layer are called packets or datagrams; and PDUs at the Data Link layer are called frames. The Physical layer uses bits.

Protocol Farm

A collection of virtual servers that are used as the primary connection point for users in an organization. The farm abstracts the connection protocols from the location of the back-end data, which allows users to access information without having to know its physical location.

Protocol Stack

A group of protocols that implements an entire communication process. TCP/IP is an example of a protocol stack.

Protocol Suite

A collection of protocols that are associated with and that implement a particular communication model (such as the DoD networking model, or the OSI reference model). Also referred to as a protocol stack.

Proxy Address

A foreign e-mail address of an Exchange recipient. Proxy Exchange users (foreign e-mail users). It would be the proxy address the non-Exchange user uses to address mail to the Exchange recipient. Proxy addresses for SMTP and X.400 are automatically generated for Exchange recipients at their creation. If the connectors for MS Mail and cc:Mail were installed, then proxy addresses for those address types would also be automatically generated for Exchange recipients.

PS/2

The range of PCs first introduced by IBM in the late 1980s.

PSE

See Packet Switch Exchange.

PSN

See Packet-Switched Network.

PSTN

See Public Switched Telephone Network.

PTR

See Pointer Record.

Publication

In SQL Server replication, a collection of articles. Subscribing servers can subscribe to an entire publication only. In earlier versions of SQL Server, it was possible to subscribe to an individual article in a publication.

Public Data Network (PDN)

Generally for a fee, a PDN offers the public access to computer communication networks operated by private concerns or government agencies. Small organizations can take advantage of PDNs, aiding them in creating WANs without investing in long-distance equipment and circuitry.

Public Folder

A folder used to store data for a group of users. Some of the features of a public folder are permissions, views, and rules.

Public Folder Affinity

A numeric value that assigns a cost to another site. When clients need to connect to public folders in another site, affinity numbers are used to choose the site to connect to.

Public Folder Replication

The transferring of public folder data to replicas of that folder on other servers.

Public Folder Tree

Also known as Public Folder Root and Top Level Hierarchy (TLH). A collection of public folders created under the same hierarchical namespace. Previous releases of Exchange server used only a single tree called All Public Folders, whereas multiple trees can be defined in Exchange 2000. Each tree is a unit of hierarchy replication and can be replicated to one or more Public MDBs. A Public MDB can host only one tree. MAPI clients such as Outlook can only access a single tree called All Public Folders, whereas other clients such as a Web browser or a networking client using the Microsoft Web Storage System can access any tree that is defined.

Public Group

See Public Role.

Public Key

The half of a key pair that is published for anyone to read and is used when encrypting data and verifying digital signatures.

Public Key Encryption

An encryption technique that uses private-public key pairs. Each actor has a public and a private key. Public keys are shared between the two parties and are used to sign and encrypt data. This encrypted data can be decrypted only by using a private key.

Public Role

A role that exists in every SQL Server database. Any rights granted to the Public role automatically apply to all users in the database, including the guest user (if present).

Public Switched Telephone Network (PSTN)

A global network of interconnected digital and analog communication links originally designed to support voice communication between any two points in the world. It was quickly adapted to handle digital data traffic when the computer revolution occurred. In addition to its traditional voice support role, the PSTN now functions as the Physical layer of the Internet by providing dial-up and leased lines for private and public use. See also Internet, Modem and Physical Layer.

Publishing Server

In SQL Server replication, the server that has the original data and is making that data available to other replication servers.

Pull

A procedure where a user finds and retrieves information, such as when browsing a public folder. Users accessing a public folder containing a company’s employee handbook is a type of pull communication.

Pull Feed

A procedure where a newsgroup server requests newsfeed information from another newsgroup server. The opposite of a push feed.

Pull Page

A model of Web-page creation in which a server-side process requests data dynamically from the database when the Web browser makes the request. No static page is created. The HTML response to the request is created dynamically by the server-side process.

Pull Partner

Pulls data from another server.

Pull Replication Trigger

A request for new data that works by sending a record number and asking for any records that are newer.

Push

A procedure where information is sent (i.e., pushed) to users. Users do not need to find and retrieve (i.e., pull) the information. Exchange Server pushes incoming messages to MAPI-based Exchange clients.

Push Feed

A procedure where a newsgroup server sends information to another newsgroup server without requiring the receiving server to request it. The opposite of a pull feed.

Push Page

A model of Web-page creation in which static Web pages are created by executing queries on a SQL Server and formatting the output in HTML. This HTML page is placed on a Web server and can be accessed by a Web browser. Although the pages can be updated frequently, they are still static pages.

Push Partner

Pushes data to another server.

Push Replication Trigger

Signals the receiving server to request the changed data.

Push/Pull Partnership

A partnership in which one server pulls while the other pushes. Often used when you want to pair up servers in even groups across a high-speed LAN connection.

Published Applications

Applications installed with Windows Installer packages. Users can choose whether or not they will install published applications through the Control Panel Add/Remove Programs icon. Administrators can choose to have published applications installed when the applications are invoked. See also Windows Installer Packages.

Publishing

Making applications available for use by users through Group Policy and Software Installation settings. Published applications can be installed on demand or when required by end users through the use of the Add/Remove Programs applet in the Control Panel.

PVC

See Permanent Virtual Circuit.

PVP

See Permanent Virtual Path.

PVP Tunneling

A technique that links two private ATM networks across a public network using a virtual path; wherein the public network transparently trunks the complete collection of virtual channels in the virtual path between the two private networks.

PWS

See Peer Web Services.

PXE

See Pre-Boot Execution Environment.