The zones contain information about all domains under the top-level domains .se and .nu that are delegated in the domain name system (DNS) and thus visible on the internet. The zone files are updated every hour and can be obtained from the nameserverzonedata.iis.se.
What is a zone file?
A zone file contains DNS information about a particular domain name, for example the names of the mailserver or webserver for the domain and, if applicable, their respective IP-addresses. The data in a zone is technical information required for the domain name to function. As such, a zone file does not contain any confidential information.
Like most top-level domains, the zones for .se and .nu are delegation centric. This means that most of the information concerns which nameservers that are authoritative for which domain names, as well as any information needed to connect to these servers. If the domain is signed, all necessary DNSSEC-data is included as well.
The registrant of a domain name registered under .se or .nu. is ultimately responsible for the delegation of said domain name. This means that it is up to the registrant (i.e., the domain owner) to provide information regarding authoritative name servers for the corresponding zone. The domain owner can operate the name servers themselves, or, more commonly, delegate the responsibility to another party, such as an internet service provider or a web-hosting provider.
Benefits through research
By providing access to our zone files, we give everyone the opportunity to perform analyses and conduct research on services available in Sweden. Thereby, we indirectly support efforts that benefit, mainly, the Swedish parts of the internet.
Questions and answers
Why don’t you just publish the list of domains?
The zone files contain all the domains that are accessible from The Swedish Internet Foundation through the DNS. A domain can be registered without delegation. As such, it contains no DNS data and will not show up in the zone file. Also, the DNSSEC information in the zone file provides verification that it originates from us and no other source.
Are there tools for interpreting the zone file?
In addition to the tools provided with DNS server software, there are a variety tools for inspecting zone files. The software idns provides numerous tools for parsing zone files in different ways, and the software can be adapted to perform customized tasks. For example, a list of domains can be extracted from a zone file through clean-zone.sh.
Will a publicly available zone file lead to more SPAM?
Any information in the DNS is considered public data and numerous tools for accessing the contents of a zone have always been available. There are ways to make it more cumbersome to extract zone data, but they are of limited use since lists of domains are easily shared between spammers. We have seen nothing to indicate that a publicly available zone file would have any impact on the volume of spam..
What do I need to consider if I want to keep the registration of a domain name secret?
If you have reasons not to reveal a domain name prior to actively using it, like when launching a campaign or a new brand, you should refrain from delegating it. As long as there is no delegation, the domain will not show up in the the zone file for .se or .nu respectively. Ask your registrar for help if you have questions about this.
Can I opt to not have my domain name included in the distributed zone file?
In order to use a domain for anything, it must be published in the zone file. If you do not want it included, you can opt to not delegate the domain. Note that some information on a registered domain can still be obtained through Whois, but only if you already know the exact domain name. It is not possible to query for a list.
Do IP addresses constitute personal data?
The IP addresses in zone files do not identify any individuals. They are infrastructure addresses and therefore to be viewed as public information. These IP addresses may, for example, be necessary to reach the authoritative name servers for a domain, in which case they are tied to the DNS operator. Apart from name servers, the addresses could belong to web servers, routers, and other equipment that makes up the infrastructure of the Internet, and likewise, they are tied to an operator. As such, they cannot be considered secret or sensitive information, and cannot be used to identify a user.
Do you provide an API for querying domains in the zone file?
The APIs (or protocols) offered by The Swedish Internet Foundation for querying domain information are DNS and Whois. DNS provides technical information about the domain, while Whois provides (limited) information about the domain owner.
How up to date is the information in the published zone file?
The zone file that we publish is identical to the one installed on our name servers. We update the zone file every hour, which means you always have access to the most recent zone data.
Where can I obtain the zone files?
The zonefiles can be obtained at zonedata.iis.se.