A big +1 to checking Spamhaus, specifically their DROP and EDROP lists. These two lists are what causes us most pain when acquiring IPv4 space as a lot of providers put auto blocking in place based on these two which can be difficult to get removed.
I won’t even contemplate prefixes on either of these lists unless the seller knocks $5/IP off the purchase price because of the associated time and pain trying to clean it up. Sent from my iPhone > On Apr 3, 2019, at 11:49 AM, Valdis Klētnieks <valdis.kletni...@vt.edu> wrote: > > On Wed, 03 Apr 2019 15:20:17 -0000, "Torres, Matt via NANOG" said: > >> 3. Check SORBS blacklisting. It should not show up except maybe the DUHL >> list(?). If it does, walk away. > > SORBS isn't the only place to check. As an example, if Spamhaus doesn't have > nice things to say about the block, it's time to start asking questions.... > > http://www.anti-abuse.org/multi-rbl-check/ has a fairly good list of > places that could give your customer a bad time (whether or not the > listing is deserved - the point is that being listed anywhere there will > probably mean problems that have to be cleaned up) > > You may all now begin the religious war over where else to check. > >
