This glossary was written and prepared by Blair Bergum of  DNSnews.net
For additions or corrections to this glossary, please send email to glossary at dnsnews dot net

You may freely link to the DNS & Internet Glossary. However, you may not reproduce this glossary in any manner, electronic or otherwise, without the express written authorization from the author. All copies of this glossary must keep this credit in place. This glossary cannot be changed, reformatted, or redistributed in any manner or fashion.

daemon

a continually running program in UNIX that handles service requests from clients. A daemon runs by itself under the OS.

DARPA

Department of Defense Advanced Research Projects Agency which gave contract to IANA for managing the Internet. This contract predates the contract awarded by the DOC to ICANN. DARPA, formerly known as ARPA, develops technological research for the U.S. military. DARPA funded much of the development which led to the Internet. http://www.darpa.mil

DAS

Direct Attached Storage. Is storage that is directly attached to the server. DAS is typically designed for less than or equal to 200GB capacity for servers in a single location. Cannot be used for shared read/writes. DAS is good for RAID-equipped database applications.

Data Binding

a function in Microsoft IE which allows a web page content to be dynamically linked to some graphical elements of an application.

Data Center

are large network facilities that house servers and are connected with multiple connections to the Internet backbone.

Data Format

Resource Records can also contain 2 and 4 octet integer values as well as domain names and or character strings. Domain Names are limited to 63 octets or less. A character string is limited to 256 characters including the length octet itself.

datagrams

1)the name of a packet in an IP network.

2)is a self contained unit of data that is transported across a network in a connectionless type protocol, such as UDP.

data integrity monitor

see host-based IDS.

data transfer

the monthly amount of data in Kbits or Mbits a web server is allowed to receive or transmit. See also bandwidth.

DCA

Defense Communication Agency is the successor of DARPA and later was renamed Defense Information Systems Agency, DISA.

DCE

Distributed Computing Environment, a logical group of hosts that share services of the Open Group's DCE.

DDN

Defense Data Network, of the U.S.

dedicated IP

see static IP

dedicated server

when a client leases a server from a host provider and the provider provides only the initial OS and web software. A dedicated server is dedicated to serving the single owner of a website or combination of websites, versus a shared server where multiple owners share server resources.

de facto standard

the fact standard that has been accepted by industry because it was the most widely used.

de jure standard

the bylaw standard that has been dictated by a supporting organization or committee such as the DNSO.

DHCP

Dynamic Host Configuration Protocol, is a protocol used for the administration of assigning IP addresses on a network DHCP allows automated administration of assigned IP addresses from a centralized location.

DHTML

Dynamic HTML, a process of creating content to dynamically creating webpages on-the-fly when the page loads into the browser. DHTML is the involves the incorporation of CSS, Scripting Language, and DOM, which can act together along with HTML to offer animated or dynamic functionality that cannot be achieved with HTML alone. DHTML is not a specification, it is an implementation of these technologies that allows web pages to become animated.

DIG

1) Domain Information Groper, a UNIX based program of the DNS to lookup zone files.  DIG  provides information about domains from a server on the DNS.

2) Blair Bergum’s DNS Internet Glossary, created by Blair Bergum in January of 2003.

digital

is the electronic technology that describes the process of transmission, where there are only two attributes, on and off, (or positive, and non-positive) denoted by the value of 1 and 0, respectively.

Digital Signal X

the term used to define the standard digital transmission rates based upon the DS0 transmission rate of 64 Kbps. Digital signal X is based upon the ANSI T1.107 guidelines. See also DS0, T-1, and T-Carrier.

Directory Service

a network service that identifies all of the resources on a network and makes those resources accessible to users.

Directory Services servers

servers that locates information specific to a network such as the data structure of the logical divisions of the network.

DISA

Defense Information Systems Agency, formerly DCA, and before that known as DARPA.

disk space

the physical space or amount of room on a server to store files and programs.

distributed database

a database where no one server stores all of the information. An example of this is the DNS, where Name Servers are distributed around the world. A distributed database provides information to the client as though it were all located in one database.

DMCA

Digital Millennium Copyright Act.

DNAME

a new form of a record in BIND 9 that allows records to work like substitution rules to simplify the setup of zone records. A DNAME record will synthesize CNAME records on the fly.

DNCRI

Division of Networking and Communication Research and Infrastructure of the NSF.

DNRC

Domain Name Rights Coalition, a public policy advocacy group concerned with the domain name rights of the registrants. http://www.domain-name.org

DNS

Domain Name System, created by Paul Mockapetris, and introduced in 1983 in RFC 882 (Note: the S stands for SYSTEM) DNS refers to the entire SYSTEM of networked servers containing the NS programs, and the clients containing the resolvers. Not to be confused with Name Service, which is only the subset of the program that does the Name to IP translation on a server. DNS has been mistakenly referred to as Domain Name Service, which is incorrect usage. DNS is:

1) a hierarchical client-server based distributed database management system.

2) used to facilitate the easier memorization of domain names over IP addresses.

3) inter-dependent upon name servers and root servers for a given zone of authority.

4) a system that requires a unique address for each domain name that is attached to the network.

DNS clients

also known as resolvers.

DNS Notify

a DNS function that allows zone change notification by allowing the primary master name server to notify the zone slaves each time the serial number is incremented.

DNS racing

a DNS-based scheme that uses a local DNS server to simultaneously send test messages to each edge server, as part of a CDN, and instructs them to reply directly to the DNS server with the actual response to the request so it can be sent back to the client. In this case all of the edge servers respond, but only the first one to respond matters, since then the request has been answered.

DNS redirection

a DNS-based scheme where DNS resource records are used to redirect a request to a NS or to call a CDN controller (acting as a NS) which in turn sends out queries to each edge server to test their speed of response time. The edge server results along with the topological proximity measurements is computed, and the edge server sends the query to the fastest edge server to complete the actual request from the client.

DNSSEC

DNS Security Extensions Code, uses public key cryptography, to enable zone administrators to digitally sign and authenticate zone data. DNSSEC is detailed in RFC 2535.

DNS servers

also known as nameservers.

DNS service provider

service provider that provides DNS management services so clients can manage their domain name records.

DNS Update

a dynamic update standard as described in RFC 2136, which allows for authorized agents to update the zone data.

DNS zone

is a portion of the DNS name space containing the database records of the DNS database record files.

DNSO

Domain Name Supporting Organization, is the advisory body to ICANN concerning policy issues of the DNS. http://www.dnso.org This organization as of January of 2003 will be renamed the GNSO.

DNSO Constituencies

Include the ccTLD Registries, BIZ Business Registry, IPC, ISP, NCDHNHC, and various other Registrars.

DNS Server

a server in the DNS of networked servers, that may be one of the Authoritative root servers, or other server that has zone information in its NS program.

DOC

United States Department of Commerce. The DOC is who gave the authority to ICANN to manage the domain name space, protocols, and IP addresses for the Internet. http://www.doc.gov

DOD

United States Department of Defense, can be found at http://www.dod.gov

DOM

Document Object Model, is a platform and language-neutral interface which allows programs and scripts to dynamically access and update content structure, and the style of documents.

domain

1) is a logical group of computer and network resources that are grouped under one security boundary.

2) the space allocated for a user on a server for the purpose of posting files for a website. Also known as a website.

3) a subtree of the domain name space, which could include the TLD, SLD, subdomain, or any contiguous portion of that domain.

domain alias

is a pointer that allows one domain name to point to the address of another domain name.

domain information groper

see DIG.

domain name

An easy to remember name-based Internet address which via the DNS is translated into an IP address. It specifically is that which is:

1) the name or identifier that proceeds the gTLD or ccTLD of a domain name, also known as the SLD.

2) the complete domain name including the TLD extension. (i.e. the SLD and the TLD, and any other subdomains).

domain name hosting

a service provider that will provide DNS software to change or update a registrant’s DNS information on the registrant’s zone record.

domain name registration company

a service provider that is otherwise known as a Registrar.

domain nameserver

a domain name that has the added functionality of performing the function as a Name Server to facilitate the resolving of a domain name request. Follows the form of ns1.nameserver.com. The name server provides the function of name service that links domain names with IP addresses and serves requests issued from the root servers to facilitate the DNS process.

domain name space

also referred to as name space, is the hierarchical representation of an inverted tree, representing the graphical diagram of all the domain names.

Domain Name System

See DNS.

domain server

the server that contains the nameserver program that contains all of the associated resource records for a domain in its zone of authority for carrying out DNS processes and queries.

dot

see period. Also see “.”

dotted decimal format

the form of an IP address. Four sets bytes, comprising from 1-3 digit numbers separated by periods, where each byte is represented by a decimal number separated by periods.

dotted octet notation

see dotted decimal format.

dotted quad

see dotted decimal notation

download

to receive or request files to be transferred from your server to your workstation.

dry-pipe

fire suppression system using halon gas rather than water.

DSL

Digital Subscriber Line, is a high bandwidth communication line that can download data at speeds between 512 Kbps to 1.544 Mbps, and upload data at speeds of 128 Kbps.

DS0

Digital Signal Designator 0 is the base standard for the digital signal X series for referring to digital transmission rates. DS0 equals a transmission rate of 64 Kbps and commonly referred to as a single voice channel.

DS0 Multiple

Digital Signal Designator Multiple, is the base standard of 64 Kbps data rate, of which all other Digital Signal Lines build upon. For example:

A DS1 is 24 times a DS0.

A DS2 is 96 times a DSO.

A DS3 is 672 times a DS0.

A DS4 is 4032 times a DS0.

DS1

Digital Signal Designator 1 is the base standard for the digital signal X series for referring to digital transmission rates. DS1 equals a transmission rate of 1.544 Mbps, 24 times the DS0 multiple. Also known as a T-1 line.

DS2

Digital Signal Designator 2 is the base standard for the digital signal X series for referring to digital transmission rates. DS2 equals a transmission rate of 6.312 Mbps, 96 times the DS0 multiple. Also known as a T-2 line.

DS3

Digital Signal Designator 3 is the base standard for the digital signal X series for referring to digital transmission rates. DS3 equals a transmission rate of 44.736 Mbps, 672 times the DS0 multiple. Also known as a T-3 line.

DS4

Digital Signal Designator 4 is the base standard for the digital signal X series for referring to digital transmission rates. DS4 equals a transmission rate of 274.176 Mbps, 4032 times the DS0 multiple. Note: There is no T-Carrier equivalent in the DS4.

duplexing

similar to mirroring, but where there are separate hard drive controllers for each duplicate hard drive, in a server designed for redundancy. Also known as RAID-1.

Dynamic DNS

a method that allows automatic registration to a DNS name space.

Dynamic HTML

See DHTML.