What is SIDN? The .nl registry and what it means for your domain

SIDN, short for Stichting Internet Domeinregistratie Nederland (the Foundation for Internet Domain Registration in the Netherlands), is the organisation in Arnhem that runs the Dutch domain extension .nl. SIDN keeps the register of more than 6 million .nl domain names, sets the rules for .nl and makes sure every .nl name can be found on the internet. You register a .nl domain through a registrar or a company that works with one, such as LJPc hosting, and that is also where you manage everything for your own domain.

This article explains what SIDN does, who handles what for a .nl domain, how to use the SIDN Whois, how to tell whether an email from SIDN is genuine, where to go with a complaint or dispute, and what dns.sidn.nl means in a DNS response. Everything about registering a .nl domain itself, including the rules, the price and transfers, is in how to register a .nl domain.

What is SIDN?

SIDN is the registry for .nl: the operator of the Netherlands' country code top-level domain. Every country has one. For Belgium it is DNS Belgium, for Germany DENIC. The key facts, according to SIDN itself:

• A foundation since 1996. Piet Beertema, Ted Lindgreen and Boudewijn Nederkoorn set up the Stichting Internet Domeinregistratie Nederland. On 31 January 1996 SIDN took over .nl registrations from the Centrum Wiskunde & Informatica (CWI), where Beertema had applied for the extension in 1986.
• Not a commercial company. SIDN puts what it earns into keeping .nl strong and secure and invests in the internet community, for example through research by SIDN Labs and through the SIDN Fund, which has backed more than 400 internet projects since 2014.
• More than 6 million .nl domains. At the end of 2025 the register held 6,059,392 .nl domain names, sold through 1,052 registrars. That makes .nl one of the largest country code domains in the world.
• More than .nl. SIDN also provides the registry services for .amsterdam and for .aw, the extension of Aruba, and develops services for a safer internet, such as its brand monitoring service.

How .nl started and grew over forty years is covered in the history of domain names and on SIDN's own page what we do.

SIDN, registrar and registrant: who does what?

Three or four parties are involved in every .nl domain. Knowing who does what tells you where to go with a question.

SIDN charges its fee for your domain to the registrar, and each registrar sets its own price for you. So you pay for your .nl domain to your registrar or reseller. That is also where you change your details, because only a registrar can update them at SIDN. Your rights and obligations as a registrant are in SIDN's general terms and conditions for .nl registrants.

For questions about your own domain, SIDN refers you to your registrar. For other questions and complaints, SIDN Support is available on working days from 08:30 to 17:00 (Amsterdam time) on +31 26 352 55 55 and at support@sidn.nl.

What SIDN's rules mean for your .nl domain

SIDN's rules decide what you can do with your domain. The main ones, with where to read more:

• Registering. Anyone can own a .nl domain, wherever they live. A name has 2 to 63 characters: letters, digits and hyphens, without accents. All the rules are in how to register a .nl domain.
• Your details. The domain is registered to the real holder, with a residential or business address. If SIDN suspects fraud, the registrant has 3 working days to prove their identity, after which SIDN disconnects or changes the name servers and the website goes offline.
• Privacy. The name and address of a private individual are not public. What is visible is explained in how to manage WHOIS data for your domain.
• Transfers. You transfer a .nl domain with a transfer token, which your registrar must give you within five days. The steps are in get your transfer code and move your domain.
• A new registrant. SIDN processes a change of registrant straight away, as described in changing the owner of a domain.
• Cancellation. A cancelled .nl domain spends 40 days in quarantine, so the previous registrant can get it back. More in expired domain, redemption period or quarantine.

SIDN Whois: how to look up a .nl domain

The SIDN Whois tells you whether a .nl name is available and, if it is taken, which registrar it is with. Type the domain name and click Check. To see the full details you accept the Whois terms of use. On the website you can check a status 2,000 times per 24 hours from one IP address. These are the statuses you can see:

The full details include the registrar, the reseller, the registrar's abuse contact, the name servers, whether DNSSEC is on, and the dates of registration and last change. For a private individual no name is shown. If your domain is with us, you will see LJPc listed as the reseller.

If you prefer the command line, use the whois command, which comes with Linux and macOS:

$ whois -h whois.domain-registry.nl 'is yourdomain.nl'
$ whois -h whois.domain-registry.nl 'yourdomain.nl'

The first command only tells you whether the name is free. The second shows the status, the registrar, the name servers, DNSSEC and the dates.

If it is your own domain and your details are wrong, update them through your registrar. At LJPc you do this yourself in the portal, as described in how to manage WHOIS data for your domain. If the details of someone else's domain look wrong, report it to SIDN Support. Need to prove that you are the registrant, for example because your old registrar does not cooperate? Then request your registrant details from SIDN, as explained in who manages your domain?

Is an email or invoice from SIDN genuine?

The invoice for your .nl domain comes from your registrar or reseller, because SIDN bills the registrars. If you receive a bill in SIDN's name, or from a company with a similar-sounding name, only pay it once you have checked where your domain is registered. How to check and where to report a fake invoice is in fake domain invoice or renewal notice.

An email from SIDN itself can be genuine. These are the situations in which you get one:

• Verification of your details. If SIDN suspects a domain is used for fraud, it emails the registrant asking them to prove their identity, with a link to SIDN's verification page. There, Signicat, the company SIDN works with, reads your passport, driving licence or identity card. The full procedure is on the page verification of registration data.
• Your registrant details. If you request your registrant details yourself, you get an email with two links that each open once.
• Sharing files. If you exchange files with SIDN, for example when reporting a security vulnerability, SIDN can send you a link to a secure environment for sharing them: secure share.

In doubt? Do not click the link in the email. Call SIDN Support on +31 26 352 55 55, the number listed on SIDN's website, and ask whether the email is genuine.

Email from SIDN about your domain goes to the email address registered with the domain. For most domains at LJPc that is a customer portal address ending in @inbox.ljpc.nl. You will find those emails under Inbox in the customer portal.

Complaints and disputes about a .nl domain

SIDN does not check new registrations against trademarks or other rights: an available name gets registered. If something goes wrong, where you turn depends on the situation:

Under the dispute resolution regulations you can only ask to become the new registrant. You succeed if you show that the name is identical or confusingly similar to a name you hold rights to under Dutch law, that the registrant has no rights or legitimate interest in it, and that they registered or use it in bad faith. The procedure is run by the WIPO Arbitration and Mediation Center. If the registrant files a defence, SIDN first appoints a mediator at no extra cost. If mediation fails, an independent expert decides instead of a court. All the steps are on SIDN's page infringement of rights.

Under Notice and Take Down, SIDN does not remove the content itself. It removes the link between the domain name and the IP address, so the site can no longer be reached through the domain name. For phishing and malware on a .nl domain, SIDN itself alerts the registrant, the registrar and the hosting company. Together they took phishing sites offline within 20 hours on average in 2025.

Seeing dns.sidn.nl, dns@sidn.nl or ns1.dns.nl?

You see these names in the output of dig or nslookup, or in a DNS test, when you look up a name that does not exist in the .nl zone. ns1.dns.nl is one of the name servers of the .nl extension, and dns.sidn.nl is the contact address in the SOA record of the .nl zone. Written as an email address, that is dns@sidn.nl. A response looks like this:

$ dig does-not-exist-example.nl MX

;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN
;; AUTHORITY SECTION:
nl.  300  IN  SOA  ns1.dns.nl. dns.sidn.nl. ...

The status NXDOMAIN means: this name does not exist in .nl. SIDN appears because the .nl zone gives the answer. So there is no fault at SIDN, and questions about your own domain go to your registrar. Check the following:

1. Is the domain name spelled correctly, including the part after the dot?
2. Is the domain registered? Look it up in the SIDN Whois.
3. Has the domain been cancelled? A domain in quarantine is no longer in the .nl zone and also returns NXDOMAIN.

If your domain does exist but your website or email does not work, the cause is usually in the domain's own name servers or records. How to track that down is in troubleshoot DNS problems with dig and nslookup. How name servers work together is in NS record explained.

What LJPc hosting handles for your .nl domain

• Registration for €11.23 a year. A .nl domain costs €11.23 a year with us, excluding VAT, with DNS management included. The order wizard in the customer portal shows straight away whether a name is available. All the steps are in register a domain and link it to your hosting.
• Transfer to us. With your transfer token you move a .nl domain to LJPc in the order wizard. You pay €11.23, which covers your first year with us. How to follow the transfer is in transfer your domain to LJPc.
• Automatic renewal. As long as the subscription for your domain runs, we renew it automatically every year.
• DNS and DNSSEC. Your domain gets our name servers ns1.ljpc.network, ns2.ljpc.network and ns3.ljpc.network, and we switch on DNSSEC automatically. How that protection works is in what is DNSSEC.
• Everything in one place. You change the registrant and your contact details yourself in the portal, and the transfer code is on your domain's page in the Authorization code block.

Unsure about an email or letter about your domain, or is a transfer stuck? Create a support ticket and we will look into it with you.