The Internet is a critical resource in the daily life of billions of users. To support the growing number of users and their increasing demands, operators continuously scale their network footprint---e.g., by joining Internet Exchange Points (IXPs)---and adopt relevant technologies---such as IPv6---which provides a vastly larger address space than its predecessor.

The business relationships between Autonomous Systems (ASes) can provide fundamental insights into the Internet's routing ecosystem. Throughout the last two decades, many works focused on how to improve the inference of those relationships. Yet, it has proven difficult to assemble extensive ground-truth data sets for validation. Therefore, more recent works rely entirely on relationships extracted from BGP communities to serve as "best-effort" ground-truth. In this paper, we highlight the shortcomings of this trend. We show that the best-effort validation data does not cover relationships between ASes within the Latin American (LACNIC) service region even though ~14% of all inferred relationships are from that region. We further show that the overall precision of 96-98 % for peering relationships achieved by three of the most prominent algorithms can drop by 14-25 % when considering only peering relationships between Tier-1 and other transit providers. Finally, we discuss potential ways to overcome the presented challenges in the future.

With the recent IPv4 address exhaustion, many networks can no longer rely on requesting additional IPv4 addresses space. They resort to new ways to obtain addresses: buying and leasing. In this paper, we first shed light on the recent economic trends of the IPv4 buying market by augmenting transfer statistics with public and private pricing information from four large IPv4 brokers. We infer the size of the IPv4 leasing market through two different data sources: routing information observed from BGP collectors and RDAP databases operated by the Regional Internet Registries. We find that neither of those sources alone is capable of estimating the full market size. We relate our findings to discussions with 13 IPv4 brokers and summarize how networks handle their demand for obtaining IPv4 addresses in 2020.

Inbound traffic engineering (ITE)---the process of announcing routes to, e.g., maximize revenue or minimize congestion---is an essential task for Autonomous Systems (ASes). AS Path Prepending (ASPP) is an easy to use and well-known ITE technique that routing manuals show as one of the first alternatives to influence other ASes' routing decisions. We observe that origin ASes currently prepend more than 25% of all IPv4 prefixes.