Analysis of Privacy Disclosure in DNS Query

When a DNS (domain name system) client needs to look up a name, it queries DNS servers to resolve the name on the Internet. The query information from the client was passed through one or more DNS servers. While useful, in the whole query transmission, we say it can leak potentially sensitive information: what a client wants to connect to, or what the client is always paying attention to. From the definition, the privacy problem is to prove that none of the private data can be inferred from the information which is made public. We first analyzed the complete DNS query process now in use; then, from each step of the DNS query process, we discussed the privacy disclosure problem in each step of the query: client side, query transmission process and DNS server side. Finally, we proposed a simple and flexible privacy-preserving query scheme "range query", which could maximally decrease privacy disclosure in the whole DNS query process. And we also discuss efficiency and implementation on the range query.