List of domains blocked via DNS filtering in India

[qurbat]

Hi all, I'm the author of "Poisoned Wells," a study looking at the scale of DNS blocking in India. Sharing the list of blocked domains produced by the work, which contains 43,083 apex domains, their categories, Tranco popularity rankings, and blocking status across 6 ISPs in India.

https://github.com/qurbat/dnsblocks.in/blob/main/data/compiled_blocklist.csv

I hope you will find it useful.

[wkrp]

Hi all, I'm the author of "Poisoned Wells"

Hello, thank you. Is this a report? Can you share a link and a brief synopsis?

Thanks for making your data accessible and reusable.

Related past issue: #361.

[qurbat]

Hi all, I'm the author of "Poisoned Wells"

Hello, thank you. Is this a report? Can you share a link and a brief synopsis?

Thanks for making your data accessible and reusable.

Related past issue: #361.

Thank you! This comes from a report that I published yesterday, examining the scale of DNS censorship in India. The measurement collection for this study occurred between March - September 2025. Here is the executive summary:

While some internet service providers (ISPs) have started to use more sophisticated
techniques to implement web censorship, Domain Name System (DNS) filtering
continues to remain a popular method for both small and large Indian ISPs. This report
presents findings from the largest study to date of DNS-based censorship in India.
The point-in-time study collected DNS measurements for 294 million registered apex
(root-level) domains across six Indian ISPs, sending 1.76 billion DNS queries in total.
Its findings offer censorship circumvention tool developers and internet freedom
researchers important insights and avenues for further investigation.

Key findings:

• A total of 43,083 unique apex domains were confirmed blocked via DNS filtering — a sixfold increase over the previous largest study (which documented 6,787 blocked domains).
• A major ISP’s misconfiguration of a blocking rule is causing significant overblocking where an entire global top-level domain (.yokohama) is inaccessible.
• Only 9,363 censored domains (21.73% of the blocklist produced by this study) had ranks in the Tranco list (a reliable and transparent top-sites ranking list), demonstrating that test lists drawing from popularity rankings do not accurately represent censorship scale.
• There is aggressive blocking of services and platforms across categories including business, hosting, research, and communication.
• A state-owned, public-sector undertaking (PSU) ISP’s consumer blocklist is hypothesized to be derived from filtering policies intended for government offices.

The project website is available at dnsblocks.in, and the report can be accessed here: dnsblocks.in/assets/report.pdf

[wkrp]

I found the table of blocking signatures interesting (Table 5):

ISP	Signature
Jio	A record pointing to 49.44.79.236
Airtel	CNAME record pointing to dotblocking.dummy (which has an A record pointing to 13.127.247.216)
ACT	A record pointing to 49.205.171.201 (resolver) or 49.207.46.62 (injection)
MTNL	A record pointing to 59.185.3.14
You Broadband	A record pointing to 203.109.71.154 and NS records pointing to ns[1-4].youbroadband.in
Connect Broadband	A record pointing to 202.164.51.25

Section 04 comments on blocking anonymization/circumvention tools:

Blocking of anonymization tools: Domains in the anonymization and circumvention (ANON) category were found to be blocked across multiple ISPs. MTNL exclusively blocked the domains of at least two popular VPN services, including Surfshark (surfshark.com, Tranco rank #1048) and AdGuard VPN (adguard-vpn.online, Tranco rank #1601). You Broadband exclusively blocked domains for Urban VPN (urban-vpn. com, Tranco rank #4279) and the VPN Gate (vpngate.net, Tranco rank #46554) service. Airtel was found to block UltraVPN (ultravpn.com, Tranco rank #194201).

Some artifacts of the study are available:

All collected measurements and resources are available at dnsblocks.in. The public blocklist release has been modified to obscure all sites classified as ICAP.

Tools:

• blockbust (wrapper around ZDNS with censorship detection utilities)
• domcat (UI for classifying domain categories)

Data:

• Raw DNS measurements (1.76 billion queries)
• Compiled blocklist, enriched with categories and Tranco ranks

Resources:

• Interactive blocklist explorer (available on the project website)

[wkrp]

A feature I'll suggest for the interactive explorer is a way to permalink a search. Like if I want to show someone the blocking data for vpngate.net, it would be nice if there were a URL query or similar to link to that search directly, without having to type in the query.

[qurbat]

A feature I'll suggest for the interactive explorer is a way to permalink a search. Like if I want to show someone the blocking data for vpngate.net, it would be nice if there were a URL query or similar to link to that search directly, without having to type in the query.

Thank you for the suggestion. This should be fairly straightforward. I'll create an issue.