Description of the NSF grant funding this project can be found here: <a href="https://www.nsf.gov/awardsearch/showAward?AWD_ID=1619048" rel="nofollow">https://www.nsf.gov/awardsearch/showAward?AWD_ID=1619048</a><p><i>This work addresses two key challenges in measuring network reliability from the outside. The first important problem is to determine whether address changes are actually the cause for a network device becoming unreachable to external measurement. The second key problem is in separating individual failures from other failures. For example, with an approaching storm, many users may disable their equipment to avoid lightning damage, but with a passing storm, an outage may affect many users at once.</i>