[dns-operations] Bulk whois/zone file access

[Doug Barton]

Pardon if this is considered off topic. Feel free to send me in the 
right direction if so.

I am working on a project for a company that would like to do some 
research on domain names that infringe on their brands/trademarks. Two 
thoughts come immediately to mind:

1. Zone file downloads from Verisign. Has anyone applied with them for 
this purpose? Results?

2. Some sort of bulk whois access. In doing some searching I came across 
https://whoisds.com/ which seems fairly reasonably priced. Anyone have 
experience with them, good or bad? Other suggestions?

Thanks,

Doug