Unveiling the Hidden Scale of Internet Blocking in India

A groundbreaking audit has exposed the massive extent of Domain Name System (DNS) censorship in India, revealing that over 43,000 domains are actively blocked across major Internet Service Providers (ISPs). Titled 'Poisoned Wells: Examining the Scale of DNS Censorship in India,' this first comprehensive study provides unprecedented insight into a shadowy practice that affects millions of users daily. Conducted by researcher Karan Saini and supported by the Internet Governance Project at the Georgia Institute of Technology, the report highlights how DNS filtering—where ISPs manipulate responses to domain queries to prevent access—has ballooned without public oversight.

DNS, the internet's phonebook that translates human-readable domain names like example.com into machine-readable IP addresses, is a common tool for censorship because it is easy to implement at the ISP level. In India, this occurs under the veil of Section 69A of the Information Technology (IT) Act, 2000, which empowers the government to issue confidential blocking orders for reasons including national security, public order, and preventing cognizable offenses. Users attempting to access blocked sites often receive no explanation, just error messages like NXDOMAIN (domain does not exist) or redirects to sinkhole IPs.

The study's revelations come at a critical time for India's digital ecosystem, where internet penetration exceeds 900 million users, yet access to information remains uneven. For academics, students, and researchers in higher education institutions across the country—from IITs to state universities—this opacity raises alarms about stifled knowledge flow.

The Rigorous Methodology Behind the Audit

To capture the true scale, the researchers compiled a list of 294,480,735 unique apex domains from sources like ICANN's Centralized Zone Data Service for generic top-level domains (gTLDs) and the Domains Project's active domains list. They then fired off 1.76 billion DNS queries—limited to A records for IP resolution—at a cautious rate of about 100 queries per second (QPS) to avoid disrupting services.

Testing spanned six prominent ISPs: Reliance Jio (AS55836), Bharti Airtel (AS9498), Atria Convergence Technologies (ACT Fibernet, AS18209), Mahanagar Telephone Nigam Ltd. (MTNL, AS17813), You Broadband (AS18207), and Connect Broadband (AS17917). Direct connections were used for Jio, Airtel, and ACT, while infrastructural resolvers—publicly exposed DNS servers belonging to the ISPs—were probed for the others, identified via tools like Censys and Shodan.

Blocking detection relied on signatures: forged IP responses (e.g., sinkholes like 127.0.0.1 or government IPs), NXDOMAIN injections, or refusals. Validation against control resolvers like Google (8.8.8.8) and Cloudflare (1.1.1.1) filtered false positives. Ethical safeguards included low query volumes, using attributable infrastructure, and reporting illegal content like child abuse material (ICAM) sites to authorities.

Post-collection, domains were categorized using an expanded Citizen Lab taxonomy, blending open-source blocklists for malware (MAL), pornography (PORN), and gambling (GMB); machine learning models; and manual review of meta-descriptions. Popularity was gauged via Tranco rankings, revealing that only 21.73% of blocked domains are in the top million sites.

A Staggering 43,083 Unique Domains Blocked

The audit confirmed 43,083 unique apex domains blocked—a sixfold jump from the prior largest tally of 6,787. This represents a lower bound, as untested domains or IP-based blocks (not DNS) could push the figure higher. Breakdown by ISP shows wide variance:

Airtel's lead stems partly from blocking the entire .yokohama gTLD (over 3,000 domains), likely a misconfiguration. Analysis of 32,451 domains tested across all six ISPs showed low consensus: only a fraction universally blocked, underscoring haphazard implementation.

Categories Dominating the Blocklist

Of the filtered blocklist, movies and TV piracy (MOV) claims 51.62%, followed by pornography (PORN) at 6.38%, file-sharing (FILE) at 5.53%, and gambling (GMB) at 3.91%. Militant/terrorism sites (MILX) are just 0.53% but boast the highest universal blocking rate at 38.60%.

• MOV: Sites like 0123movies.com blocked universally.
• PORN: Scattered enforcement, low consensus.
• FILE: Torrent hubs prevalent.
• HOST: Free hosting like 000webhost.co.

Uncategorized (UNCAT) and hosting blocks suggest broader collateral. Hosting and business sites face aggressive filtering, impacting legitimate operations.

Overblocking: Innocent Sites Trapped

Overblocking plagues the system. MTNL targets expired domains, '1004' prefixed sites, Korean IDNs, and even gov.in sites like mes.gov.in (Ministry of Education?) and rera-punjab.gov.in. Jio blocks TikTok infra and uol.com.br. ACT ignores a 2022 unblock for videolan.org.

You Broadband censors research staples: Scribd, SlideShare.net, Academia.edu—vital for Indian scholars sharing papers. Airtel's TLD blanket-ban exemplifies errors. Researcher Saini notes, 'Blocking orders are confidential... creating a basic gap in public knowledge.' Users get no alerts, fostering distrust.Explore the interactive blocklist.

Critical Impacts on Higher Education and Research

For India's 1,000+ universities and millions of students, DNS blocks erode access to knowledge. Platforms like Academia.edu and SlideShare, blocked by You Broadband, host theses, slides, and collaborations essential amid high journal paywalls. Elsevier and Springer subscriptions strain budgets, pushing reliance on such sites.

Recent Sci-Hub blocks exacerbate this; a 2025 Delhi High Court order halted the 'shadow library,' sparking outcry from researchers fearing stalled innovation. Studies show Indian academics download heavily from Sci-Hub, with blocks risking productivity drops in resource-poor institutions.

Students in remote areas, dependent on open resources, face barriers. VPN circumvention exists but requires KYC under new rules, deterring casual use. Explore higher ed jobs in India where digital access shapes career paths, or university positions amid evolving tech needs. Career advice for academics stresses resilient research habits.

The Legal Framework: Secrecy Under Section 69A

India's IT Act empowers the Ministry of Electronics and Information Technology (MeitY) to block content via non-judicial orders, kept secret except appeals. From 2015-2022, 55,607 URLs were targeted per reports. ISPs comply without user notice, choosing DNS for simplicity despite alternatives like IP blocks.

Courts occasionally intervene, like unblocking MediaNama in 2021, but opacity persists. No appeals for end-users, chilling speech. Global watchdogs like Freedom House note rising blocks.

Stakeholder Perspectives and Reactions

Karan Saini emphasizes underestimation: prior popularity-biased lists missed 78% of blocks. ISPs like Airtel and MTNL ignored queries. Advocacy groups hail the dataset for transparency. Academics decry research hits; one physicist tweeted, 'Sci-Hub ban was bad; this scale is worse for collab.'

Businesses lament hosting blocks disrupting CDNs like Let’s Encrypt. No government response yet, but calls grow for audits.

Global Comparisons and Broader Ramifications

India's 43k dwarfs smaller nations but trails China's Great Firewall. Like Russia's DNS poisoning, India's lacks sophistication, leading to leaks. Economic toll: stifled startups, e-commerce. For free expression, it fragments info, especially news like Kashmir Walla (universally blocked post-2023).

In higher ed, parallels U.S. paywall debates but amplified by Global South dynamics.ThePrint coverage.

Path Forward: Solutions and Outlook

Recommendations: Default DNS over HTTPS (DoH) in browsers/apps for encryption bypass; non-standard ports like Quad9:9953 evade injections. Policymakers urged judicial oversight, public lists.

For researchers, diversify access via institutional VPNs, open archives. India's digital ambitions demand balance. Check rate my professor for insights on navigating restricted resources, or higher-ed-jobs, higher-ed-career-advice, university-jobs, post-a-job to advance amid challenges. Future monitoring via Saini’s project promises sustained scrutiny.

Photo by Tapan Kumar Choudhury on Unsplash