Hi, While I think #3 is important, it depends on your use of the end-block, and those entries can sometimes be cleaned up with some work. If the block is listed, that would certainly lower my buying price I am willing to pay for the block. I did buy a block once in the ARIN region which showed up in IP geolocation databases as Russian (no idea why), but it took me quite a while to get it fixed. Sincerely, Jeffrey Hathaway Information Technology * Howard Center Inc. From: NANOG <nanog-bounces@nanog.org> On Behalf Of Torres, Matt via NANOG Sent: Wednesday, April 3, 2019 11:20 AM To: nanog@nanog.org Subject: Purchasing IPv4 space - due diligence homework All, Side stepping a migration to IPv6 debate.... I'd like to hear advise from the group about performing due diligence research on an IPv4 block before purchasing it on the secondary market (on behalf of an end-user company). My research has branched into two questions: a) What 'checks' should I perform?, and b) what results from those checks should cause us to walk away? My current list is: 1. Check BGP looking glass for route. It should not show up in the Internet routing table. If it does, walk away. 2. Check the ARIN registry. The longer history without recent transfers or changes is better. I don't know what explicit results should cause me to walk away here. 3. Check SORBS blacklisting. It should not show up except maybe the DUHL list(?). If it does, walk away. Anything else? Advise? Thanks, Matt ________________________________ HowardCenter.org<http://howardcenter.org> [http://howardcenter.org/assets/design/Facebook.jpg] <http://www.facebook.com/pages/HowardCenter/106516727431> [http://howardcenter.org/assets/design/Twitter.jpg] <https://twitter.com/HowardCenterVT> [http://howardcenter.org/assets/design/LinkedIn.jpg] <http://www.linkedin.com/company/HowardCenter> CONFIDENTIALITY NOTICE: This e-mail is intended only for the use of the individual or entity to which it is addressed and may contain information that is patient protected health information, privileged, confidential and exempt from disclosure under applicable law. If you have received this communication in error, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. Please notify the sender by reply e-mail and delete the original message immediately, or notify Howard Center, Inc. immediately by forwarded e-mail to our Privacy Officer, DaveK@howardcenter.org. Thank you.