Microsoft Windows XP Networking Inside Out

between the two can be established. If the ARP broadcast fails to determine the physical address of the target computer’s network adapter, an error message is generated. See also MAC address.

Advanced Digest Authentication

Advanced Digest Authentication is a lightweight process that permits secure authentication of users across network security devices (such as firewalls). It does not require client-side software and does not send user credentials in a clear-text format over public networks. IIS supports Advanced Digest Authentication.

AppleTalk AppleTalk is a networking protocol developed by Apple Computer, Inc. for communication between Apple Macintosh computers.

authentication The process of verifying the identity of a user or computer to grant access to the local computer or network resources. Authentication is typically performed by checking a user name and password, often in conjunction with other security protocols, such as EAP and MS-CHAP.

Automatic Private IP Addressing (APIPA) A service that automatically assigns IP addresses to network clients when no DHCP server is available. When a Windows 2000 or Windows XP computer starts up, it makes a DHCP query in an attempt to get a network address. If the DHCP server fails to answer, APIPA is used by the client to assign an IP address in the range of 169.254.0.1 to 169.254.255.254. This particular range of addresses was set aside for use by the Internet Assigned Numbers Authority (IANA) for use only on private, internal networks.

B

bandwidth The speed of transmission of a digital communications system as measured in bits per second.

bridge A hardware device (or piece of software) that connects two physically dissimilar networks, such as an Ethernet network and a Token Ring network, or an Ethernet network and a wireless network. Windows XP includes a feature known as Network Bridge that can function as a software bridge.

C

cable modem A device that connects a computer or local area network to a broadband network that shares the same cable used to deliver cable television. Cable modems are used primarily to deliver broadband Internet access. Some cable companies use a shared access method, where bandwidth is shared among users in certain areas or neighborhoods. In many new cable implementations, there is so much bandwidth available that performance is usually not a problem.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

A contention-based network media access method. Using CSMA/CD, network hosts listen for traffic on the network and attempt to transmit data as soon as no traffic is heard. If multiple hosts transmit at once, a collision occurs, and all transmitting hosts retry their communications. See also token passing.

Challenge Handshake Authentication Protocol (CHAP) An encrypted authentication mechanism that does not transmit the password in clear text across the initial connection. Instead, a handshake process allows the client to prove its identity. A revision of CHAP, MS-CHAP revises the authentication process to supply specific information needed to authenticate to Windows networks.

client A computer that connects to another remote computer (often called a server) to request resources such as files or remote printers. See also server.

cluster The smallest amount of disk space that can be allocated to hold a file (or a portion of a file) on a disk. Smaller clusters allow disk space to be more efficiently utilized, but increase the amount of disk activity (and therefore time) required to open large files.

compression The process of shrinking files and folders by removing redundant data. Lossless compression is fully reversible in that the original data is perfectly restored when the file is subsequently decompressed and accessed. NTFS supports lossless compression of files, folders, and drives in Windows XP.

cookie A small text file that Web servers place on a user’s computer to later identify the individual on subsequent Web site visits; often used to customize the browser’s return experience. Although cookies facilitate personalized settings for each Web site, they are also a potential source of personal information theft, unsolicited e-mail (or spam), and undesired tracking of Internet use. Internet Explorer 6 contains cookie management features that can help control cookie usage and protect privacy.

crossover cable A cable that directly connects two computers for networking purposes without an intervening hub or other network device. The crossover cable looks like a Category 5 cable, but the wires are reversed so that direct communication can take place.

D

denial of service attack (DoS) A network attack intended to make its target, either local or remote users, unable to function properly. DoS attacks normally work by crashing a computer or network service, or by overloading it so heavily that it becomes unresponsive.

dial-up connection Any connection that uses a device called a modem to communicate over a telephone line. Dial-up connections are often used to access the Internet as well as RAS servers on corporate networks. See also modem.

Digital Subscriber Line (DSL) A broadband Internet access method that runs over standard copper telephone wiring using different channels to transmit and receive data at much higher speeds than a traditional analog dial-up modem. DSL circuits must be supported by the user’s phone company, and the user must live within a certain distance of the telephone company’s switching office to use DSL. Most data services use asymmetric DSL (ADSL), which divides the phone line into three channels. One channel is used for voice, whereas the other two channels are used for data transmission and reception. Symmetric DSL (SDSL) is a variant that provides equal upload and download speeds.

direct cable connection (DCC) A direct computer-to-computer connection that uses

a crossover cable, a parallel cable, or a null modem cable to connect two computers for networking purposes. When only two computers need to network, DCC is an inexpensive option. DCC can also be used when two computers need to temporarily network with each other.

DNS server A DNS server resolves Domain Name System requests sent by remote clients. DNS servers maintain databases of local host-name-to-IP address mappings and can also communicate with remote DNS servers to resolve remote addresses. See also Domain Name System.

domain controller A special server computer in a Windows domain that authenticates users on the network and provides security and other network resources. Microsoft Windows domain controllers run server versions of the Windows operating system, such as Windows NT, Windows 2000, and later releases.

Domain Name System (DNS) A hierarchical, distributed database that maps host names to IP addresses. These DNS mappings enable the user to find a computer by supplying the destination’s user-friendly domain

name (such as www.microsoft.com or detroit.support.tailspintoys.com) and letting a DNS server resolve (look up) the fully qualified domain name (FQDN) into its associated IP address (such as 192.168.3.42), which is the address format actually used to route traffic over TCP/IP networks. TCP/IP networks include Windows networks as well as the Internet.

domain A Microsoft network that uses one or more Windows servers designed to manage the network and provide network services for Windows clients. A domain contains one or more domain controllers that hold the user account database as well as other information about network services. Additional servers can be used to provide other administrative services for the domain or to serve files to users on the network.

Dynamic Host Configuration Protocol (DHCP) A protocol used to automatically configure client IP address information for computers when they join a network. DHCP specifies the manner in which the DHCP client and server negotiate an address for the client’s use. The process of assigning addresses involves a DHCP server and a DHCP client. The DHCP server holds information about the address range in use, the remaining addresses available, the network gateway, the DNS server addresses, the WINS server addresses, and other administratively configurable options.

A particularly important function of the DHCP server is to administer the lease period. The lease period is the amount of time that any DHCP client is allowed to keep its address without checking in with the server. At the end of the lease, the client must query the server

to see if the address is still valid.

E

Encrypting File System (EFS) A feature of NTFS that encrypts files so that hackers and even system administrators cannot view them.

It can be enabled for single files or entire folders (and subfolders). EFS also includes features to decrypt files in case an original user’s encryption keys are lost. See also encryption.

encryption The process of scrambling data in a complex and reversible way to provide security to data residing on a computer or traversing a network. A key is required to decrypt and read the data. See also Encrypting File System.

Ethernet A network protocol that specifies the interface design (how the cable jacks and adapter receptacles should be built) and signaling process for LAN communications. Ethernet uses a signaling scheme known as CSMA/CD and operates at a capacity of 10 Mbps or greater. See also Carrier Sense Multiple Access with Collision Detection.

Extensible Authentication Protocol (EAP) An authentication method that provides security extensions so that administrators can employ alternative security technologies, such as smart cards or biometric devices, for users logging on to the network.

F

FAT32 file system The most recent version of Microsoft’s FAT file system. FAT32 can be used as an optional file system for Windows XP and is also accessible by many other operating systems including Windows 95 OSR2, Windows 98, and Windows Millennium Edition (Me). FAT32 lacks many of the advanced features offered by NTFS. See also file allocation table; NTFS file system.

Fiber Distributed Data Interface (FDDI) A fiber-optic LAN/WAN networking technology that is capable of 100 Mbps transfer. FDDI works much like a Token Ring network, but two rings are used, providing redundancy should the primary ring fail.

file allocation table (FAT) A file system developed by Microsoft for its MS-DOS operating system and later used by Windows. FAT file systems rely on an allocation table that specifies where clusters containing files are located. See also FAT32 file system; NTFS file system.

File Transfer Protocol (FTP) A protocol used to move files from one computer to another. In addition to moving files from one place to another, FTP can be used to perform basic file management tasks such as creating directories, deleting files and directories, and renaming the contents of directories.

firewall A solution provided by software or a hardware device that protects a LAN or WAN from attacks that originate from hosts outside the protected network. Firewalls can employ a number of methods to protect an internal network, including table access, port filtering, and network address translation (NAT). Windows XP includes a software firewall called Internet Connection Firewall (ICF). See also Internet Connection Firewall; network address translation.

Fortezza A security standard outlined by the United States government to ensure that software systems meet the requirements of the Defense Message System architecture. This architectural specification encompasses cryptography, confidentiality, data integrity, authentication, and access control requirements. Fortezza is supported by Internet Information Server in Windows XP Professional.

G

gateway The device or computer that maintains a network’s connection to other networks or to the Internet. Without a default gateway, TCP/IP traffic cannot be routed to other networks.

Group Policy A management tool that enables network administrators to control computer configurations as well as user accounts and applications. With Group Policy, network administrators can control desktop settings, Internet Explorer settings, applications, security settings, and many other settings on desktop computers in a Windows domain environment. Local Group Policy can be implemented on stand-alone computers or those in a workgroup setting; however, in a domain environment, it can be overridden by policies specified at the OU or domain level.

H

HomePNA A networking technology that uses a home or small office’s existing telephone lines as the network infrastructure. HomePNA adapters use RJ-11 phone jacks and plug directly into the existing telephone cabling. The HomePNA network is capable of 10 Mbps transfer and does not interfere with standard voice conversations.

hub A device that connects networked computers to one shared network segment. All devices connected to the hub share the same bandwidth. By definition, hubs contain no intelligence and simply connect multiple computers to a network electrically. See also switch; router.

Hypertext Transfer Protocol

(HTTP) The protocol used to transfer Web pages from one location to another. HTTP specifies the way that a client and server interact when transferring content such as Hypertext Markup Language (HTML) code for the purpose of displaying a Web page in a user’s browser software.

I

Identities A feature in Microsoft Outlook Express 6 in which multiple identities can be created so that different users can have different mail folders. By specifying a different

identity, each user can access their personal mail. However, in Windows XP, if different user accounts are created for each user, identities are not necessary because each user has his or her own Outlook Express mail folder. User accounts also provide greater privacy than using multiple identities in Outlook Express.

IEEE 802.11b At the time of this writing, the most common wireless network standard. 802.11b networks operate with a maximum speed of 11 Mbps using radio waves.

IEEE 802.1x A standard for providing port-based authentication for wired and wireless Ethernet networks.

infrared A method of performing wireless network communications using infrared light. Infrared networks typically adhere to the Infrared Data Association (IrDA) standards.

Institute of Electrical and Electronics Engineers (IEEE) An organization of engineering professionals who develop standards for hardware and software. See also IEEE 802.11b; IEEE 802.1x.

Integrated Services Digital Network (ISDN) An older network dial-up technology that uses existing phone lines (without the distance limitations of DSL) to provide digital speeds of typically 64 Kbps up to 128 Kbps. ISDN is not as popular today because consumers are favoring faster, cheaper, and always-on connections such as DSL and cable.

Internet Connection Firewall (ICF) A software firewall solution included in Windows XP. ICF is designed to protect Windows XP (as well as any other computer sharing the same Internet connection) from unwanted outside network access or attacks.

Internet Connection Sharing (ICS) A feature provided in Windows XP that allows one computer to share its connection to the Internet with other computers on the local network. See also network address translation.

Internet Control Message Protocol (ICMP) A diagnostic and maintenance protocol used on TCP/IP networks. Applications using ICMP include Ping, Tracert, and PathPing.

Internet Information Server (IIS) A full-featured software suite that enables the creation and hosting of Web, FTP, and SMTP services. The version included in Windows XP Professional allows up to 10 concurrent connections and is designed for developing Web sites or hosting small intranet sites.

Internet Protocol (IP) A routable networking protocol for addressing and routing network traffic; part of the TCP/IP suite of Internet networking protocols.

Internet Protocol Security (IPSec) A standard for securing TCP/IP communications. IPSec includes facilities for authentication, key exchange, and traffic encryption. See also Layer Two Tunneling Protocol; virtual private network; Kerberos authentication.

Internet service provider (ISP) A company that provides Internet access to users for a fee.

Internet The world’s largest public network, containing millions of hosts and Web sites.

Internetwork Packet Exchange (IPX)

A routable protocol used by Novell for its NetWare operating system; an optional protocol that can be installed in Windows XP.

K

Kerberos authentication An openstandard authentication mechanism used to securely authenticate users, typically over a public medium such as the Internet. Kerberos allows computers as well as users to be uniquely identified without transmitting identification data in clear text (which could be intercepted). See also Internet Protocol Security.

L

latency The time required for data to travel from one point to another on a network.

Layer Two Tunneling Protocol (L2TP)

A standard for establishing virtual private network (VPN) communications across the Internet. See also Internet Protocol Security.

local area network (LAN) A network situated in one geographical location, often in one building. A LAN can be a workgroup consisting of only a few computers, or it can be a large domain consisting of thousands of computers. See also wide area network.

M

Media Access Control (MAC) address An addressing scheme that uniquely identifies individual physical network adapters on a network whether those adapters are connected to a computer or a network management device.

metabase A repository of configuration information for IIS as well as any sites being served from a particular IIS installation.

network address translation (NAT)

A process of converting IP addresses; most often used to allow one public IP address to be shared by multiple systems, each of which has only a private IP address. NAT features are often included for address management and security purposes in residential gateway devices.

Network File System (NFS) A file system designed to allow diskless workstations to mount file systems from other computers.

These mounted file systems appear to be local to the user and all of the applications running on the workstation. NFS uses a collection of remote procedure calls (RPCs) operating over UDP and TCP to affect connectivity. NFS is widely used as the protocol for sharing and connecting to files and folders on UNIX-based networks.

network share A resource, such as a directory or a printer, provided by a Windows computer for access by other network users.

network A collection of computers organized to share resources and data without manually transferring them via removable media.

NetBIOS Extended User Interface (NetBEUI) A network protocol created by IBM and supported in Windows XP for routing network traffic. It has been largely supplanted in Windows XP by TCP/IP.

NetBIOS The default application programming interface used for networking in earlier versions of Windows. Originally combined with NetBEUI (which is still supported), it can be paired with other networking protocols such as IP and IPX. NetBIOS uses 15-character names to identify individual computers.

network adapter A device that enables a computer to be connected to a network; sometimes referred to as a network interface card (NIC).

NTFS file system The file system of choice for Windows XP computers. NTFS provides file-level security as well as additional features, such as compression and encryption. See also FAT32 file system; compression; Encrypting File System.

null modem cable A cable used to connect two computers using their serial ports. The computers then communicate over the cable directly rather than through a network hub. The null modem cable provides a good temporary network solution, but it is too slow for permanent networking needs and is limited to connecting only two computers.

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O

Offline Files A Windows XP Professional feature that provides local access to remote files when the local computer is disconnected from the network. This situation might occur during an outage or when a portable computer is removed from the network for mobile use. The user can continue to work with the cached copies of the offline files. Windows XP synchronizes the local and network copies when the computer is reconnected to the network.

organizational unit (OU) An object used in Active Directory domains for management and organizational purposes. An OU can be delegated to different administrators who can then manage its contents. OUs can contain network resources such as users, groups, printers, shared folders, and other data.

P

Point-to-Point Protocol (PPP) A remote access protocol that provides features such

as authentication, encryption, and protocol encapsulation that allow remote users to connect to a network via dial-up or other methods. PPP is the basis for the PPTP and L2TP protocols. See also Layer Two Tunneling Protocol.

Point-to-Point Protocol over Ethernet (PPPoE) A type of broadband Internet connection that is not always connected, but instead requires a user name and password to connect. To conserve IP addresses, many ISPs offering broadband services now use PPPoE so that the user is logged out when the connection is not in use.

Point-to-Point Tunneling Protocol (PPTP) A Microsoft protocol for establishing virtual private network (VPN) connections over networks such as the Internet. See also virtual private network.

Password Authentication Protocol (PAP) A clear-text authentication scheme in which a server asks for a user name and password from a client computer that is attempting to log on. PAP submits the data in clear-text format, which makes this type of authentication insecure.

performance counter Measures the activity of a certain portion of a performance object when using the Performance tool in Windows XP. The Performance administrative tool is useful for monitoring and troubleshooting network performance

on a computer-by-computer basis.

performance object A grouping of related computer activities in the Windows XP Performance tool from which specific performance counters can be selected to monitor and troubleshoot Windows networks.

Powerline networking A networking technology that uses a home or small office’s electrical lines for networking purposes. Powerline adapters plug directly into a wall receptacle, and the building’s existing electrical cabling is used for networking.

private folder In Windows XP, a private folder prevents all users of the particular computer, including any computer administrators, from viewing the contents of the folder. The private folder is an additional Windows XP method for securing information locally when Simple File Sharing is in use.

protocol A standard for network communication. A protocol defines the ways in which network data is transmitted, routed, and processed.

R

remote access The dial-up process of connecting to a remote server and being authenticated by that server so access to a remote network is possible. Windows 2000 networks use remote access servers so that dial-in clients can access the network.

router A device that directs traffic between networks. A router examines the destination address for data and determines which of its remote network ports is best suited to receive that data. See also hub; switch.

S

Remote Assistance A new feature in Windows XP that allows another networked computer (local or Internet) to use Terminal Services to see the desktop of a computer user who needs assistance (known as a novice). The novice sends an invitation for help to a user designated as the expert. The expert can connect to the novice’s computer, see the novice’s desktop, and even take control of the computer to fix the problem, if the novice grants permission.

Remote Desktop A new Terminal Services feature of Windows XP Professional. Using Remote Desktop, a user can access an enabled remote computer and control the remote computer through a terminal window as if logged on locally.

residential gateway A device used on home or small office networks that manages traffic between the Internet and the LAN. Many residential gateways include additional features and functions, such as DHCP leasing of IP addresses and firewall functions including NAT.

RJ-11 The connector type used to connect telephones to phone jacks. Some home networking options, such as HomePNA, use RJ-11 connectors to connect computers to a home’s existing telephone wiring and use that wiring to create a local area network without disrupting telephone usage.

RJ-45 The connector type used to connect twisted-pair Ethernet cabling to Ethernet jacks.

satellite Internet An Internet access system that includes a special modem, satellite equipment, and a satellite dish to provide broadband Internet access. Upload speeds are significantly slower than other broadband technologies, but satellite Internet is usually available where no other broadband solutions exist. The only requirement is that the dish have a clear line-of-sight to the area of the sky in which the satellite is located.

Secure Sockets Layer (SSL) An encryption algorithm used to secure network traffic; commonly used by secure Web servers.

Server Message Block (SMB) A filesharing protocol that enables a network computer to access files located on other network computers. Windows XP supports the SMB protocol.

server A network computer that performs an administrative function for the network. Some servers are responsible for authenticating the credentials of users who attempt to log on to the network, while others might hold applications and data and serve them to authenticated network users on demand.

Simple File Sharing A new feature included in Windows XP that offers an easy way to configure the sharing of certain resources over the local area network so that other users can either read or have full access to shared resources. Simple File Sharing is enabled by default, but in Windows XP Professional, it can be disabled in favor of using more sophisticated NTFS permissions. It cannot be disabled in Windows XP Home Edition.

Simple Mail Transfer Protocol (SMTP) The current protocol standard for host-to-host mail transport. SMTP specifies how communication works between a mail

server and its end users. Its main function is to facilitate the delivery of e-mail from one server to another.

Simple Network Management Protocol (SNMP) A protocol that was developed to provide a standard method of assessing information about the health of a network device as well as remotely configuring the device.

switch A device that connects multiple networked devices together, providing each device connected to the switch with full dedicated connections to the other connected devices. See also hub; router.

T

Telnet An insecure protocol designed to provide remote access to a computer by performing terminal emulation, thus allowing a user to communicate with a computer as though he or she were typing directly at a local console. Telnet is a text-only protocol and is used primarily by UNIX-based systems. Telnet sends all data, including user names and passwords, in clear text; its use should be avoided for security reasons.

topology Term used in networking to describe the physical placement of computers, cables, hubs, routers, and so forth.

Transmission Control Protocol (TCP) A connection-oriented networking

protocol; part of the TCP/IP suite of network protocols.

Transmission Control Protocol/Internet Protocol (TCP/IP) A suite of protocols for communicating across large routed networks like the Internet; originally developed by the United States Defense Advanced Research Projects Agency (DARPA).

U

User Datagram Protocol (UDP) A sister protocol to TCP. Whereas TCP was developed to provide connection-oriented service and a means of error detection and compensation, UDP was designed for maximum throughput. UDP depends on the physical component of the network to be reliable or for other protocols to compensate for any data loss. As a result of this simplicity, UDP has very little communications overhead and is particularly useful when it is more important for data to arrive quickly than reliably, such as in delivering streaming media.

token passing A technique for controlling network access. With token passing, only one computer at a time possesses the token, which gives it the right to transmit data on the network. Once transmission has successfully occurred, the token is passed to the next computer. The token always moves around the network sequentially, ensuring that all computers have an opportunity to transmit. See also Carrier Sense Multiple Access with Collision Detection.

Token Ring A type of network that uses token passing techniques to control network access. See also token passing.

V

virtual private network (VPN) A network that encapsulates data securely and transmits it over a public network, thus providing access to a secured remote private network without exposing important data to interception. See also Point-to-Point Tunneling Protocol; Layer Two Tunneling Protocol; Internet Protocol Security.

W

wide area network (WAN) A network that is dispersed over several geographic locations, often worldwide in scope.

Wi-Fi Popular name for wireless network technologies using radio waves for communication. See also IEEE 802.1b.

Windows Internet Naming Service (WINS) A protocol developed to provide a standard for resolving NetBIOS names to their associated IP addresses.

Windows Messenger The instant messaging program included with Windows XP. Windows Messenger can be used to conduct instant messaging, voice messaging, and even video sessions with Whiteboard collaboration or application sharing.

Wired Equivalent Privacy (WEP)

A security standard that uses an encryption key as a means for securing wireless network traffic.

wireless access point A wireless networking device used to create and manage wireless networks in infrastructure mode and to bridge wireless and wired networks.

wireless local area network (WLAN) A local area network built using wireless networking technologies.

wireless metropolitan area networks (WMAN) A wireless network that enables communication between different locations within a single metropolitan area.

wireless personal area networks (WPAN) A network that resides in one small (personal) space, such as a single room. WPANs are used for networking devices in individual rooms or small homes as well as connecting individual electronic components (such as digital cameras and computers) for data transfer purposes.

wireless wide area network

(WWAN) Wide area networks that are connected by wireless means. Global System for Mobile Communications (GSM), Cellular Digital Packet Data (CDPD), and Code Division Multiple Access (CDMA) are examples of common wireless technologies that can be used by WWANs.

workgroup A small collection of computers that are networked together to share resources. Workgroups generally reside in homes and small offices and generally contain fewer than 20 computers. Each computer is administered individually, and there is no centralized security or management between the computers. However, workgroups are highly effective ways to share resources. One example of such sharing involves using Internet Connection Sharing (ICS) to share a single connection to the Internet.