  One of the primary ways in which India engages in online censorship is by
ordering Internet Service Providers (ISPs) operating in its jurisdiction to
block access to certain websites for its users. This paper reports the
different techniques Indian ISPs are using to censor websites, and investigates
whether website blocklists are consistent across ISPs. We propose a suite of
tests that prove more robust than previous work in detecting DNS and HTTP based
censorship. Our tests also discern the use of SNI inspection for blocking
websites, which is previously undocumented in the Indian context. Using
information from court orders, user reports, and public and leaked government
orders, we compile the largest known list of potentially blocked websites in
India. We pass this list to our tests and run them from connections of six
different ISPs, which together serve more than 98% of Internet users in India.
Our findings not only confirm that ISPs are using different techniques to block
websites, but also demonstrate that different ISPs are not blocking the same
websites.
