I’m new user of CIS. Besides the antivirus definition download issue, everything is great. I’m just wondering if CIS also provides Web Guard (many free antvirus, say, Avast, AVG, etc also provides Web Guard function) or link scanner functions. After all, it is called “Internet Security”. 
It doesn’t have none of these things. Comodo’s idea is that it is enough protection to detect when a malware is to be written to disk or in memory. That helps to keep it lean and mean (responsive).
It’s a design choice.