The Domain Name System (DNS) does not provide query privacy. Query obfuscation schemes have been proposed to overcome this limitation, but, so far, they have not been evaluated in a realistic setting. In this paper we evaluate the security of a random set range query scheme in a real-world web surfing scenario. We demonstrate that the scheme does not sufficiently obfuscate characteristic query patterns, which can be used by an adversary to determine the visited websites. We also illustrate how to thwart the attack and discuss practical challenges. Our results suggest that previously published evaluations of range queries may give a false sense of the attainable security, because they do not account for any interdependencies between queries.
 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. Privacy leaks are an unfortunate and an integral part of the current Internet domain name resolution. Each DNS query generated by a user reveals -- to one or more DNS servers -- the origin and the target of that query. Over time, users' communication (e.g., browsing) patterns might become exposed to entities with little or no trust. Current DNS privacy leaks stem from fundamental features of DNS and are not easily fixable by simple patches. Moreover, privacy issues have been overlooked by DNS security efforts (such as DNSSEC) and are thus likely to propagate into future versions of DNS. In order to mitigate privacy issues in DNS, this paper proposes a Privacy-Preserving DNS (PPDNS), that offers privacy during domain name resolution. PPDNS is based on distributed hash tables (DHTs), an alternative naming infrastructure, and computational private information retrieval (cPIR), an advanced cryptographic construct. PPDNS takes advantage of the DHT index structure to provide name resolution query privacy, while leveraging cPIR to reduce communication overhead for bandwidth-sensitive clients. Our analysis shows that PPDNS is a viable approach for obtaining a reasonably high level of privacy for name resolution queries. PPDNS also serves as a demonstration of blending advanced systems techniques with their cryptographic counterparts. Name services are critical for mapping logical resource names to physical resources in large-scale distributed systems. The Domain Name System (DNS) used on the Internet, however, is slow, vulnerable to denial of service attacks, and does not support fast updates. These problems stem fundamentally from the structure of the legacy DNS.This paper describes the design and implementation of the Cooperative Domain Name System (CoDoNS), a novel name service, which provides high lookup performance through proactive caching, resilience to denial of service attacks through automatic load-balancing, and fast propagation of updates. CoDoNS derives its scalability, decentralization, self-organization, and failure resilience from peer-to-peer overlays, while it achieves high performance using the Beehive replication framework. Cryptographic delegation, instead of host-based physical delegation, limits potential malfeasance by namespace operators and creates a competitive market for namespace management. Backwards compatibility with existing protocols and wire formats enables CoDoNS to serve as a backup for legacy DNS, as well as a complete replacement. Performance measurements from a real-life deployment of the system in PlanetLab shows that CoDoNS provides fast lookups, automatically reconfigures around faults without manual involvement and thwarts distributed denial of service attacks by promptly redistributing load across nodes. The rise of new Internet services, especially those related to the integration of people and physical objects to the net, makes visible the limitations of the DNS protocol. The exchange of data through DNS procedures flows today into hostile networks as clear text. Packets within this exchange can easily be captured by intermediary nodes in the resolution path and eventually disclosed. Privacy issues may thus arise if sensitive data is captured and sold with malicious purposes. We evaluate in this paper two DNS privacy-preserving approaches recently presented in the literature. We discuss some benefits and limitations of these proposals, and we point out the necessity of additional measures to enhance their security.