Project: Introducing Domain Watchdog

As we approach the end of 2025, I’d like to introduce an open-source project that has kept me busy for much of the year. Its development began over two years ago and, although many features are already in place, it remains a work in progress.

If you already follow my projects, you have probably guessed it: I am talking about Domain Watchdog, a tool designed to monitor domain names, perform structured lookup operations, receive notifications as soon as a change is detected, and even attempt automatic name registration when domains reach expiration and are deleted by the registry.

Project Launch

I hesitated for a long time before launching the development of this project, mainly because it relies on technologies that are still relatively recent. For instance, the RDAP Protocol was officially adopted to replace WHOIS in 2023, following a global vote organized by ICANN.

If you are discovering this article without being familiar with the concepts of WHOIS or RDAP, let’s take a moment to set the context and explain the essential concepts.

Technical Context

When registering a domain name, several players are involved.

First, the registrar : this is the company from which you purchase your domain name and which handles its billing and day-to-day management.

Next, the registry : this is the entity responsible for managing a Top-Level Domain, whether it is a country-code TLD like .fr or a gTLD such as .com or .net. For example, .com and .net are operated by VeriSign, Inc.

WHOIS: The Old Standard

WHOIS is a publicly accessible service that allows users to consult the registration information of a domain name. It is notably used to check if a domain is already registered and, if so, to obtain certain associated information.

The WHOIS protocol is defined by RFC 3912 , published in September 2004. It relies on a very simple mechanism: the exchange of plain text over a TCP connection. Originally, it was designed primarily for human consultation rather than automated machine processing.

As an example, here is a query sent to the .fr registry to obtain information regarding the domain maelgangloff.fr. The registry in charge of this country code Top-Level Domain (ccTLD) is AFNIC (Association Française pour le Nommage Internet en Coopération).

echo -n "maelgangloff.fr\r\n" | netcat whois.nic.fr 43

%%
%% This is the AFNIC Whois server.
%%
%% complete date format: YYYY-MM-DDThh:mm:ssZ
%%
%% Rights restricted by copyright.
%% See https://www.afnic.fr/en/domain-names-and-support/everything-there-is-to-know-about-domain-names/find-a-domain-name-or-a-holder-using-whois/
%%
%%

domain:                        maelgangloff.fr
status:                        ACTIVE
eppstatus:                     active
hold:                          NO
holder-c:                      N32690-FRNIC
admin-c:                       N32690-FRNIC
tech-c:                        N32690-FRNIC
registrar:                     Infomaniak Network SA
Expiry Date:                   2026-01-19T17:24:19Z
created:                       2021-01-19T17:24:19Z
last-update:                   2024-02-12T08:22:34.35795Z
source:                        FRNIC

nserver:                       ns41.infomaniak.com
nserver:                       ns42.infomaniak.com
source:                        FRNIC

key1-tag:                      38534
key1-algo:                     13 [ECDSAP256SHA256]
key1-dgst-t:                   1 [SHA1]
key1-dgst:                     08EC42180FFB9AD58E6DD1B0A27F8235C35D9CD3
source:                        FRNIC

key2-tag:                      38534
key2-algo:                     13 [ECDSAP256SHA256]
key2-dgst-t:                   2 [SHA256]
key2-dgst:                     6D5203C0B2550C32CE1D3A3A92D1902AE06531863C4A77224D1D923A61D70CA2
source:                        FRNIC

registrar:                     Infomaniak Network SA
address:                       Rue Eugène-Marziano, 25
address:                       CH-1227 LES ACACIAS
country:                       CH
phone:                         +41.228203544
fax-no:                        +41.228203546
e-mail:                        abuse@infomaniak.com
website:                       https://www.infomaniak.com
anonymous:                     No
registered:                    2014-06-23T00:00:00Z
source:                        FRNIC

nic-hdl:                       N32690-FRNIC
type:                          ORGANIZATION
contact:                       Domain Privacy Trustee SA
address:                       Domain Privacy Trustee SA
address:                       Rue Eugène-Marziano 25
address:                       1227 Genève
country:                       CH
phone:                         +41.225935007
e-mail:                        contact@domainprivacytrustee.ch
registrar:                     Infomaniak Network SA
changed:                       2024-06-09T12:20:22.367623Z
anonymous:                     NO
obsoleted:                     NO
eppstatus:                     serverUpdateProhibited
eppstatus:                     associated
eligstatus:                    ok
eligsource:                    REGISTRAR
eligdate:                      2024-06-09T12:20:22.367626Z
reachstatus:                   ok
reachmedia:                    email
reachsource:                   REGISTRAR
reachdate:                     2024-06-09T12:20:22.367627Z
source:                        FRNIC

>>> Last update of WHOIS database: 2025-12-19T22:00:04.864301Z <<<

This WHOIS response clearly illustrates the significant amount of information returned by certain registries. This is particularly true for so-called thick registries, such as .fr, unlike thin registries like .com or .net, which provide much less data about registrants, domain owners, or associated contact information.

On this subject, in one of the articles published by AFNIC, expert Stéphane Bortzmeyer explains in detail the difference between these two categories of registries. To delve deeper into the topic, I invite you to read this article on the AFNIC website.

Domain Watchdog is intentionally not compatible with the WHOIS protocol. In the absence of a standardized response schema, automated data analysis is complex, fragile, and difficult to maintain over time.

To learn more, a page dedicated to WHOIS is also available in the project documentation.

RDAP: The New Standard

WHOIS is increasingly being supplemented—and in many contexts replaced—by RDAP, in line with ICANN requirements.

Unlike WHOIS, RDAP is a protocol based on HTTP and provides structured responses in JSON format. The protocol and its data models are defined by several RFCs, notably RFC 9082 , which specifies the RDAP query format, RFC 9083 , which defines the JSON response structure, and RFC 7484 , which explains how clients discover the authoritative RDAP service for a given resource. Together, these specifications make RDAP responses far easier to interpret and process automatically than traditional WHOIS output.

For example, the RDAP response for the same domain maelgangloff.fr is accessible here.

The data provided by RDAP is generally equivalent to that of WHOIS, but its standardized structure is a major advantage for tools like Domain Watchdog.

To learn more, a page dedicated to RDAP is also available in the project documentation.

Future of the Project

The project has evolved significantly since its inception and has moved beyond the MVP stage. Domain Watchdog now enables the retrieval of detailed domain name information, triggers alerts when new events are detected, and can automatically attempt to register a domain name as soon as it is deleted by the registry.

The next step is to gather as much user feedback as possible in order to further refine existing features and improve the overall user experience.

This is an open-source project, feel free to contribute and suggest improvements!

If you’re running domains at scale or interested in domain lifecycle automation, your feedback would be especially valuable.

Data Analysis

The data collected in the demo instance database can also be leveraged for statistical analysis. For instance, it can be used to study DNSSEC adoption across registrars or TLDs, or to analyze patterns in DNS server reuse.

Acknowledgments

I would like to thank Vincent H. for his invaluable and constant help since the beginning of the project.

Finally, I also want to thank all the contributors, current and future, who participate in improving Domain Watchdog and making it available to users and self-hosters.