The Spamhaus SBL is a realtime database of IP addresses, described by Spamhaus as covering "spam sources, including known spammers, spam gangs, spam operations and spam support services." It lists IP addresses exclusively. This is the detail that separates it from the Spamhaus DBL, which lists domain names and nothing else.
Being listed on one says nothing about the other. A dedicated sending IP with a bad history can carry an SBL listing while every domain sending through it is untouched on the DBL, and a domain can be DBL-listed for how it appears in message content while the sending IP itself has no SBL history at all.
Spamhaus names snowshoe spam patterns (ranges and domains with poor or frequently changing identification), spam hosting and bulletproof hosting services, and outright security infrastructure (botnet controllers, malware hosts, phishing sites) as SBL triggers. The list updates roughly every five minutes and holds on the order of 30,000 to 40,000 active entries at any time.
Because the SBL evaluates the IP itself, a shared or previously reassigned IP can carry a listing earned entirely by a prior tenant, independent of anything the current sender has done. This is the same underlying mechanism as shared IP reputation damage generally, just expressed as a formal blocklist entry instead of a soft placement problem.
Not necessarily. The SBL lists IP addresses and the DBL lists domain names, evaluated on different evidence. A dedicated IP with a bad sending history can be SBL-listed while the domain sending from it is clean, and the reverse is equally possible.
Spam trap hits are one input Spamhaus can use toward an SBL listing, not a separate list of their own. The SBL itself is described as a database of IP addresses of spam sources, spam gangs, and spam support services generally.
Yes. Since the SBL evaluates the IP itself, a shared or previously reassigned IP can carry a listing earned by whoever sent from it before you, independent of your own sending practices.