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The Internet ecosystem comprising of thousands of Autonomous Systems (ASes) now include Internet eXchange Points (IXPs) as another critical component in the infrastructure. Peering plays a significant part in driving the economic growth of ASes and is contributing to a variety of structural changes in the Internet. IXPs are a primary component of this peering ecosystem and are playing an increasing role not only in the topology evolution of the Internet but also inter-domain path routing. In this dissertation we study and analyze the overall affects of peering and IXP infrastructure on the Internet. We observe IXP peering is enabling a quicker flattening of the Internet topology and leading to over-utilization of popular inter-AS links. Indiscriminate peering at these locations is leading to higher endto-end path latencies for ASes peering at an exchange point, an effect magnified at the most popular worldwide IXPs. We first study the effects of recently discovered IXP links on the inter-AS routes using graph based approaches and find that it points towards the changing and flattening landscape in the evolution of the Internet’s topology. We then study more IXP effects by using measurements to investigate the networks benefits of peering. We propose and implement a measurement framework which identifies default paths through IXPs and compares them with alternate paths isolating the IXP hop. Our system is running and recording default and alternate path latencies and made publicly available. We model the probability of an alternate path performing better than a default path through an IXP iii by identifying the underlying factors influencing the end-to end path latency. Our firstof-its-kind modeling study, which uses a combination of statistical and machine learning approaches, shows that path latencies depend on the popularity of the particular IXP, the size of the provider ASes of the networks peering at common locations and the relative position of the IXP hop along the path. An in-depth comparison of end-to-end path latencies reveal a significant percentage of alternate paths outperforming the default route through an IXP. This characteristic of higher path latencies is magnified in the popular continental exchanges as measured by us in a case study looking at the largest regional IXPs. We continue by studying another effect of peering which has numerous applications in overlay routing, Triangle Inequality Violations (TIVs). These TIVs in the Internet delay space are created due to peering and we compare their essential characteristics with overlay paths such as detour routes. They are identified and analyzed from existing measurement datasets but on a scale not carried out earlier. This implementation exhibits the effectiveness of GPUs in analyzing big data sets while the TIVs studied show that the a set of common inter-AS links create these TIVs. This result provides a new insight about the development of TIVs by analyzing a very large data set using GPGPUs. Overall our work presents numerous insights into the inner workings of the Internet’s peering ecosystem. Our measurements show the effects of exchange points on the evolving Internet and exhibits their importance to Internet routing.

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The need to protect information systems or assets remains crucial today. Innovations in technology have led to rapid developments and as technology continues to advance, so is the need to protect information systems. Amongst numerous effects of cyber-attacks on organizations, huge financial losses which in turn affect the economy have since been reported. Cyber security audits need to be strengthened to tighten the protection of information systems. The importance of cybersecurity audits is widely endorsed in literature. Nonetheless, frameworks used to audit cybersecurity are viewed as‘sometimes' weak links to cybersecurity due to their drawbacks in auditing cyber security. A review of literature indicated that cyber-attacks are more rampant in the African continent with the financial sector being the most targeted. Literature also highlighted that the use of relevant frameworks for auditing cyber security improves the quality and effectiveness of audits thereby enhancing cyber security. Studies in information systems have mostly looked at the adoption of frameworks, types of cyber threats and tools needed to audit. Nonetheless, it is important to note that few scholars have examined the applicability and effectiveness of the existing frameworks in auditing cyber security. Furthermore, previous studies emphasize on enhancing cyber security without a particular focus on auditing cyber security including assessing the role of the auditor during the process. As a result, this study looked at cyber security from an auditing perspective with a particular focus on the strengths and weaknesses of the current frameworks that are being used to audit cyber security including. The study also looked at the factors that enhance the effectiveness of cyber security audits. The study draws from different theories, literature and from the strengths and drawbacks of existing frameworks to create an explanatory model. To statistically test and evaluate the model, a quantitative research approach was employed to collect, analyze, and interpret data from South Africa. Data was collected using a questionnaire which was distributed to IT auditors and cyber security professionals from the Information Systems Audit and Control Association (ISACA) South African chapter members. The National Institute of Standards and Technology (NIST) cyber security framework was found to be the widely adopted framework followed by the International Organization for Standardization (ISO) standards, with the Control Objectives for Information Technologies (COBIT) being the least employed framework. The COBIT framework was found to be more aligned to Information Technology governance rather than cyber security. Furthermore, results of this study indicate that effectiveness of cyber security audits is dependent upon competencies of auditors including their ethics and integrity. Results further indicate that frameworks used for auditing are effective to some extent if properly implemented. A proper alignment of an auditor's competencies which include ethics and integrity, and an adoption of a relevant framework will result in effective cyber security audits that reduce the risks of cyber-attacks. Concerning the contribution to practice, results from this study can help organizations to determine and review focus areas of cyber security auditing that they need to emphasize and develop on. Furthermore, the developed model can be used by auditors to develop an audit plan and conduct audits that are effective in identifying, protecting, detecting, preventing, and recovering information systems or assets. The methodological, theoretical, and practical contributions are further discussed in this thesis along with limitations, recommendations, and areas for future research.

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As more and more companies use the internet to grow their businesses and sales, it is crucial to have a fast and responsive site that keeps customers on the site. Hence, comparing two web frameworks with respect to response time is vital, as it is a significant part of delivering the page. The comparison will help developers to choose between Express.js and Ktor. Our research shows how the two frameworks, Ktor and Express.js, compare in response times for static and dynamic pages for a set of concurrent users. The comparison will explain how the frameworks’ response times change when having a different number of concurrent users and delivering static vs. dynamic content. An experiment with Locust was conducted to obtain the data needed to show the differences in response time for the two frameworks. Additionally, a literature study was conducted to find the best way to structure the servers, design the tests, and find information on how the frameworks should perform. We found that Express.js has an overall better response time than Ktor. At the same time, it was found that the Object Relational Mapper used with Ktor affected result more than the Object Relational Mapper used with Express.js. Hence, we conclude that Express.js is the better choice, but since both frameworks had low response times, we would say that even Ktor is a valid choice.

Metal-Organic Frameworks (MOFs) are hybrid materials and are acknowledged as an important class of functional solid-state materials with high scientific interest in academia and industry alike. Their modular nature in terms of structural and compositional diversity, tunability, high surface area, and controlled pore size renders MOFs as the ideal candidate to address various persistent challenges pertaining to gas storage/separation, catalysis, drug delivery, and smart sensing. Through the field of reticular chemistry, targeted structures can be constructed through multiple design approaches, based on preselected building blocks prior to the assembly process. This thesis illustrates the merit of the supermolecular building layer (SBL) approach for the rational construction and discovery of highly connected and porous MOFs based on rare earth cations. Specifically, the emphasis of this study is on (i) the rational design and synthesis of 3-periodic MOFs based on SBLs pillared by ditopic ligands through post-synthetic modification (PSM) and in situ reactions. (ii) The investigation of the mixed-ligand system with different lengths and geometry of ditopic ligands on the isolation of metal clusters with distinct pore sizes. (iii) Gaining an overall insight into the exploration of different synthetic pathways that control the assembly of rare earth MOFs.