I’m trying to get a reverse DNS entry for one of the IP addresses which Comcast has allocated to my business. Is it possible?

It actually is very possible! I just spoke with a very helpful tech support specialist who was able to create rDNS entries for my entire /28 block within 15 minutes. To keep it simple, I just mimicked their patterns, but replaced the domain name with my own, so I could use my own DNS servers to create A records for the PTR.

Now another 15 minutes later, the records are already active. How cool is that?

Its interesting, but there appears to be quite a difference between the consumer Comcast and business Comcast IP networking services, which I am very happy about!