Hebrew University of Jerusalem Boston University USA National Institute of Standards and Technology Fastly Workonline Communications This document recommends ways to reduce the forged-origin hijack attack surface by prudently limiting the set of IP prefixes that are included in a Route Origin Authorization (ROA). One recommendation is to avoid using the maxLength attribute in ROAs except in some specific cases. The recommendations complement and extend those in RFC 7115. The document also discusses the creation of ROAs for facilitating the use of Distributed Denial of Service (DDoS) mitigation services. Considerations related to ROAs and origin validation in the context of destination-based Remotely Triggered Discard Route (RTDR) (elsewhere referred to as "Remotely Triggered Black Hole") filtering are also highlighted.