Given the importance of the Internet, it is crucial to assess its key characteristics (e.g. performance, stability, and resiliency) through measurement as it expands and evolves over time. Measuring different characteristics of the Internet is challenging mainly due to its scale and heterogeneity. Capturing and characterizing Internet topology offers the critical insight not only for understanding the physical infrastructure of the Internet but also for examining the impact a wide range of more subtle characteristics that depend on the topology such as routing, end-to-end performance, and resiliency to attacks or disruptions.

This area exam reviews a large body of recent studies on capturing and characterizing various aspects of the Internet topology as well as studies that explore implications of Internet topology on other real-world problems. To this end, we organize the prior studies on Internet topology based on their considered resolution into four groups as follows: (i) AS-level, (ii) router-level, (iii) PoP-level, and (iv) physical-level. For each group of studies, we discuss proper measurement tools and techniques, common datasets, relevant characteristics, related challenges and main findings at that resolution. We also broadly categorize studies on the implications of Internet topology based on whether they focus on performance, resiliency, or network peering relationship aspects of the Internet. We primarily describe how topology information with a particular scope and specific resolution serve as input to study more subtle aspects of the Internet. Finally, we present how the increasing popularity of cloud services in recent years have led to significant changes in Internet topology that motivate further measurement-based studies.