• Abuse contact

    A network operator’s contact address, which can be used to get in touch with the operator if you are being troubled by traffic from that network, e.g. excessive network traffic (DOS attack) or spam.

  • Access provider

    An organisation that provides internet access for its clients. Many access providers provide other services as well, such as e-mail, web hosting and spam filtering.

  • Admin-c

    Admin-c stands for ‘administrative contact’: the person registered as the point of contact for administrative matters concerning a .nl domain name. SIDN uses the admin-c’s e-mail address in automated processes involving the domain name. If, for example, a request is received to cancel the domain name or to transfer it to another registrar, the relevant notices are sent to the admin-c.  

  • Affiliate

    If you would like to be closely involved with SIDN, but you do not wish to become a registrar, you have the option of becoming an affiliate. The benefits of affiliation:

    • You have access to the restricted-access area of SIDN’s website, where information for registrars is published.

    • You receive the news updates that SIDN sends to registrars and others.

    • You are invited to SIDN Contact Days.

    • You receive our magazine, The.nlyst.


    Abbreviation of American Standard Code for Information Interchange. Computers ‘understand’ only numbers, so a code is needed for identifying letters, figures and punctuation marks by numbers; ASCII is an internationally recognised code that does just that.

  • C&AB

    C&AB stands for Complaints & Appeals Board. The C&AB is an independent body set up by SIDN, which .nl registrants and registrars can turn to if they want to appeal against a decision made by SIDN. A complaint can also be made to the C&AB if a domain name is considered to be inconsistent with public order and/or decency. Read more on cvkb.nl

  • ccTLD

    Abbreviation of ‘country-code top-level domain’: a top-level domain that is specific to a country. An obvious example of a ccTLD is .nl. A ccTLD always consists of two letters, usually the alpha-2 code letters associated with the country in the international standard ISO 3166-1.


    CENTR is an association of the organisations that register country-code top-level domain names (ccTLDs). SIDN is one such organisation. CENTR provides a discussion forum for policy that relates to the registration of ccTLDs. It also serves as a channel for communication with bodies involved in the (ongoing) development of the internet, such as ICANN. Any organisation that registers ccTLDs may join CENTR. Based in Brussels, CENTR has been registered as a not-for-profit organisation since 2006. Read more at centr.org.

  • Configuration

    The collection of hardware and software that together form a computer system or network.

  • Cookies

    A small text file written onto your hard drive when you visit a website. A cookie may contain information such as the date and time of your visit, the names of the pages you have viewed and/or details of the products you have bought.

  • Delegated

    A delegated domain name is a registered domain name that is included in the DNS. An undelegated domain name is a domain name that has been registered, but isn’t included in the DNS.

  • Dictionary attack

    An attempt to hack into a computer system by trying countless words from a dictionary as passwords.

  • DNS

    Abbreviation of Domain Name System or Domain Name Server. The global DNS is the system and protocol used on the internet to translate domain names into IP addresses and vice versa. 


    DNSSEC stands for Domain Name System Security Extensions: a suite of extension to the DNS designed to stop criminals from diverting internet users to forged websites. It has been developed because the existing DNS protocol is not completely secure. Experts have discovered that it is possible to fill a domain name server’s temporary memory (cache) with false information, so that domain names are no longer associated with the right IP addresses. Read more about DNSSEC.

  • Domain name

    A domain name is a name within the Domain Name System (DNS), the system for identifying networks, computers, web servers, mail servers and other applications on the internet by name.

  • Domain name within DNS

    A domain name is a name within the Domain Name System (DNS), the system for identifying networks, computers, web servers, mail servers and other applications on the internet by name.

  • DRS

    DRS is an abbreviation for Domain Registration System, the system that SIDN uses to create and manage registrations for .nl domain names.

  • EDNS

    EDNS is an extension to the DNS protocol, which enables longer DNS responses to be sent. This extension is used mainly in the context of DNSSEC, for which longer responses are always required.

  • ENUM

    Abbreviation of Electronic Number Mapping: a technology that brings together telephony and the internet by registering phone numbers as domain names. This makes it possible to, for example, forward e-mail messages to a mobile phone, or text messages to an e-mailbox.

  • EPP

    EPP is a protocol for registering domain names and updating existing registrations. SIDN uses EPP as a basis for communication between registrars and the Domain Registration System (DRS).

  • Extension

    The last part of an internet address, after the final dot. Many extensions – such as ‘.nl’ for the Netherlands and ‘.fr’ for France – indicate the nationality of the websites that have them.

  • Glue record

    Before a new name server can be used, a glue record needs to be created for the name server at the registry. Glue records provide information on a name server, such as the IP address and responsible registrar, and prevent a chicken-and-egg problem with DNS resolution: without a glue record, it would not be possible to initially locate a name server to ask it for information about itself and the domains it serves.

  • gTLD

    Abbreviation for generic Top Level Domain. A generic top level domain is a non-geographical domain, such as .com, .org, .info etc.

  • IANA

    The Internet Assigned Numbers Authority (IANA) is an organisation with responsibility for the global coordination of various matters that are vital to the working of the internet.   IANA’s tasks include publishing the root zone file, the assignment and maintenance of various standard number sets and protocols that enable computers to communicate with one another over the internet. IANA also manages information about top-level domains, in particular country-code domains and generic domains such as .com, .org and .biz. Read more at iana.nl.


    In order to contact another computer over the internet or to view a website, you need to use an address – either a domain name or an IP address. This address has to be unique to prevent confusion amongst internet-connected computers. The Internet Corporation for Assigned Names and Numbers (ICANN) acts as the global coordinator of this system of unique identifiers. ICANN is a not-for-profit organisation. Its responsibilities include creating ‘top-level domains’ (a TLD is the part of a domain name that comes after the final dot), assigning domain names and distributing IP addresses. Set up on 18 September 1998, ICANN is not there to prevent spam, police internet content or manage domain names. The management of domain names is the business of organisations such as SIDN (for .nl) and VeriSign (for .com and .net). Read more at icann.org.

  • IETF

    The Internet Engineering Task Force (IETF) is a large and open international community concerned with ongoing development of the internet’s ‘architecture’ and with making the internet work more smoothly. In principle, any interested party can join the IETF, whose members include network designers, operators, suppliers and researchers.

    The internet is a set of agreements that enable physical computer networks and applications to communicate with one another. Internet standards relate to the rules, procedures and technical format and protocol specifications that determine how the internet works. It is important that such matters are standardised, so that computers ‘speak the same language’ when they try to communicate with each other.   The IETF develops internet standards, which are then examined by the Internet Engineering Steering Group, in consultation with the Internet Architecture Board.   Read more at ietf.org.

  • Internet Governance Forum

    Founded in 2006, the Internet Governance Forum (IGF) is part of the United Nations. It is an umbrella for an annual gathering of governments, market players and community organisations. The IGF provides a setting for international discussion on a wide variety of policy-related matters affecting the internet. It does not itself define policy, however.   Within the IGF, public policy issues are debated with a view to ensuring that the internet remains manageable, robust, secure and stable, and is therefore able to continue to develop. So, for example, the IGF seeks to facilitate the resolution of problems associated with the use and abuse of the internet – especially the problems often encountered by ordinary users. The IGF also advises on ways of making the internet available to (and affordable for) developing countries, and on the resources needed to make this possible. Read more at intgovforum.org.

  • Internet service provider

    An ISP provides access to the internet for other organisations and individuals. Many ISPs provide other services as well, such as e-mail, web hosting and spam filtering.

  • Internet Society (ISOC)

    The Internet Society (ISOC) is an international organisation that promotes global cooperation and coordination in connection with the internet, as well as related technologies and applications. Within ISOC, 180 countries and sixteen thousand internet professionals are represented. Many ISOC members were involved in the internet’s creation.

    ISOC is a leading player in the development and expansion of the internet. It is also the parent organisation for other international bodies, including the IETF, which is engaged in the development of internet standards.


    ISOC’s Dutch offshoot, ISOC.nl, brings together about eight hundred individual members from the internet industry, the business community, the government, consumer organisations, the not-for-profit-sector, the technology sector and the financial, legal and academic worlds. ISOC.nl receives financial and practical support from numerous businesses and institutions in the Netherlands. Read more on isoc.nl

  • IP-adres

    Internet Protocol address. A unique number combination, made up of numbers and/or letters. Every computer or server on the internet has its own IP address, which enables other internet-connected devices to find it. You can find out what the IP address of the computer you are using is by visiting the website whatismyip.com.

  • IPv4

    The abbreviation IPv4 stands for Internet Protocol version 4. The maximum number of unique addresses that can be created under IPv4 is about 4.3 billion. IPv6, on the other hand, can be used to create an almost infinite number of addresses.

  • IPv6

    The abbreviation IPv6 stands for Internet Protocol version 6. IPv6 can be used to create an almost infinite number of addresses. (in contrast with IPv4: maximum number of unique addresses that can be created under IPv4 is about 4.3 billion.)


  • Is-functie

    A query service accessible from SIDN’s website, which can be used to find out the current status of a .nl domain name. The user can see whether a name is available for registration, or cannot be registered because, for example, it is inadmissible or excluded from registration.

  • ISP

    Abbreviation of Internet Service Provider. An ISP provides access to the internet for other organisations and individuals. Many ISPs provide other services as well, such as e-mail, web hosting and spam filtering.

  • Label

    A label is an individual element of a domain name or host name. For example, the name ‘www.example.nl’ has three labels: ‘www’, ‘example’ and ‘nl’.

  • Malware

    Malware is ‘malicious software’. Malware is a general term that covers computer viruses or worms, but also any other software whose purpose is dishonest or harmful.

  • MX-record

    A Mail Exchange record directs e-mail to the server that handles e-mail traffic for a given domain.

  • Name server

    To use a domain name, you need a name server. A name server is an internet-connected computer whose job is to ‘translate’ domain names into IP addresses (unique numbers for identifying devices on the internet). A name server is part of the global domain name system.

  • NCSC

    NCSC is the Dutch government’s National Cyber Security Centre. The NCSC fleshes out the integral approach and brings existing initiatives together. Ensuring digital security is the task of various parties and the NCSC acts as the link which binds together the many different activities.

  • NS record

    Name Server records determine which servers exchange DNS information for a domain.

  • Phishing

    Phishing is an internet-based criminal activity. It involves sending e-mails and setting up websites that look as though they come from or belong to well-known and trusted organisations, when in fact they are forgeries. The forged messages and sites encourage people to part with information, such as log-in details, credit card numbers and/or other personal data, which the criminals then use for their own purposes.

  • Quarantaine

    Quarantine is a period of forty days following the  cancellation of a .nl domain name, during which the name is available for  re-registration only by its ‘old’ registrant. In other words, no one else can  snap it up and start using it the moment it is cancelled. It becomes available  to ‘new’ registrants only at the end of the quarantine period.

  • Registrant

    The person or organisation to whom a domain name is registered. The registrant is the only party who is entitled to services from SIDN.

  • Registrar

    The organisation that communicates with SIDN on behalf of a (potential) domain name’s registrant. Most registrars are providers of hosting, internet or access services.

  • Registry

    A registry is an organisation that administers a TLD. For example, SIDN is the registry for the .nl TLD, and VeriSign is the registry for .com. The registry administers the registrations of all the domain names within the relevant TLD. It is also responsible for the stability of the TLD. As well as registering and issuing domain names, the registry makes it possible for internet users all over the world to use those names at any time.

  • RFC

    Abbreviation of Request For Comments: a document setting out a protocol or other agreement relating to the way the internet works.


    RIPE NCC stands for Réseaux IP Européens Network Coordination Centre. The organisation is what is known as a Regional Internet Registry (RIR). An RIR is responsible for issuing IP addresses for a particular geographical area. Responsibility for issuing IP addresses is divided amongst a small number of RIRs around the world.   RIPE NCC manages the ‘address zone’ for Europe and the Middle East. There are four other RIR's besides RIPE NCC: APNIC for Asia and Australia, AfriNIC for Africa, LACNIC for Latin America and ARIN for North America.


    For an internet provider to obtain IP addresses of its own, it needs to be a member of RIPE NCC. The provider then becomes a ‘Local Internet Registry’ (LIR). As well as issuing IP addresses and other numeric identifiers, the NCC maintains a database recording all IP address registrations in its zone.   Read more at ripe.net.

  • Server

    A powerful computer with a fast connection, which is set up purely to provide information. A web server is connected directly to the internet.

  • SOA-record

    A State Of Authority record specifies various DNS-technical parameters, such as who manages the corresponding zone, how long the information about a domain name may be stored, and how often the information is updated in the DNS.

  • Subdomein

    A subdomain is the part of an internet address that sometimes comes before the domain name (in most cases ‘www’). A web address that includes a subdomain will often look something like this: http://subdomain.domain-name.nl.

  • TCP

    TCP stands for Transmission Control Protocol: a connection protocol that is widely used on the internet. One of the characteristics of TCP is that it allows for data to be sent in a stream, thus ensuring that the data arrives in the same form it was sent, and that any communication errors, involving either the data content or the data sequence, can be dealt with. Consequently, a client application that uses TCP as its transmission protocol does not need to take account of the underlying network architecture or of possible communication errors.

  • Tech-c

    Tech-c stands for ‘technical contact’: the person registered as the point of contact for technical matters concerning a .nl domain name. Sometimes the tech-c is the domain name’s registrant (or someone working for the registrant). In other cases, it is the registrar (or someone working for the registrar).

  • TLD

    Abbreviation of Top Level Domain: the last part of a domain name, which comes after the final dot. This letter combination can refer to a country (e.g. ‘.nl’ for the Netherlands) or a type of organisation (e.g. ‘.com’ for a commercial organisation, or ‘.net’ for a public network).

  • Token

    A token is a code that is used to validate the transfer of a .nl domain name. It consists of a random series of characters linked to the domain name in question. A token always contains twelve characters, which are a mixture of numbers, lower-case letters and upper-case letters.

  • Top-level domain

    The last part a domain name, which comes after the final dot. This letter combination can refer to a country (e.g. ‘.nl’ for the Netherlands) or a type of organisation (e.g. ‘.com’ for a commercial organisation, or ‘.net’ for a public network).

  • Traffic shaping

    The limitation of internet traffic by a provider in order to prevent the network being overloaded.

  • Typosquatting

    Typosquatting is a form of internet abuse, which takes advantage of the fact that people sometimes make mistakes when typing website addresses into their browsers. The typosquatter sets up a website using an address (domain name) that is very similar to the address of a popular ‘genuine’ site. Then, anyone who accidentally types the nearly-correct address into a browser arrives at the typosquatter’s site instead of the genuine site. The people who run typosquatting sites usually have commercial motives, such as advertising. Sometimes, however, typosquatting sites are used for fraud in the form of phishing.

  • Unix command line

    A user can give the operating system (Unix, but also Windows or DOS) a command. Most commands can be qualified using various options.


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