The amount of data hosted by Internet servers and data centers is increasing at a remarkable pace requiring more capable and more e cient servers. However, physical e ciency does not necessarily correlate with computational e ciency. In fact, independent studies reveal that Internet servers are mostly over provisioned even though additional servers are deployed each year. Understanding the char...

The Domain Name System (DNS) is a critical component of the modern Internet. It provides a critical link between human users and Internet routing infrastructure by mapping host names to IP addresses. The DNS is a hierarchy of distributed system of servers anchored at 13 DNS root servers. In this paper we examine the macroscopic connectivity between the DNS root servers and the worldwide populat...

In the present study, we analyze the multi-channel service system with ordered entryfrom finite-source and finite-storage at each channel. The arrival and service rates are assumedto be state dependent. The steady state probabilities of the system are obtained by usingChapmann-Kolmogorov equations. Some other performance indices viz. utilization of servers,expected number of units in the system...

This paper presents the design and implementation of DFQ (Distributed Fair Queueing), a distributed system for defending a replicated set of HTTP servers against application-level distributed denial of service (DDoS) attacks. By using a modification of weighted fair queueing, all clients are guaranteed a fair share of the servers, no matter how many or which servers they connect to. DFQ continu...

Private information retrieval (PIR) gets renewed attentions due to its information-theoretic reformulation and its application in distributed storage system (DSS). The general PIR model considers a coded database containing N servers storing M files. Each file is stored independently via the same arbitrary (N,K)-MDS code. A user wants to retrieve a specific file from the database privately agai...

When a user requests content from a cloud service provider, sometimes the content sent by the provider is modified inflight by third-party entities. To our knowledge, there is no comprehensive study that examines the extent and primary root causes of the content modification problem. We design a lightweight experiment and instrument a vast number of clients in the wild to make two additional DN...

Electronic Medical Records (EMR) in academic medical centers often have additional complexity to them due to structural and organizational differences. Often the hospital operates independent of the medical school such as the physicians often work for the medical school, while the nurses and other ancillary departments work for the hospital. Such differences require special consideration when m...

In recent years, cyberattacks using command and control (C&C) servers have significantly increased. To hide their C&C servers, attackers often use a domain generation algorithm (DGA), which automatically generates names for the servers. Accordingly, extensive research on DGA detection has been conducted. However, existing methods cannot accurately detect continuously generated domains c...

We consider online routing optimization problems where the objective is to minimize the time needed to visit a set of locations under various constraints; the problems are online because the set of locations are revealed incrementally over time. We consider two main problems: (1) the online Traveling Salesman Problem (TSP) with precedence and capacity constraints and (2) the online TSP with m s...