To get the best results with Comodo Leak Test (CLT), follow these steps:
1) Make sure you have the following CIS settings:
> CIS configuration is set to "Proactive"
> Firewall set to "safe mode" or "custom policy mode"
> Defense + set to "safe mode" or "paranoid mode"
> Image execution activated (CIS 5 = "enabled"; CIS 4 = "normal" or "aggressive")
> Detect shellcode injections = enabled
> Defense+ monitoring settings = all boxes checked.
2) Make sure you do not have any CLT rules in CIS, which may have been added if you had previously run CLT. Remove the rules using the instructions shown in this post
for CIS 4 and this post
for CIS 5.
3) Empty the internet explorer (IE) cache/history ("Impersonation: Coat" test can fail when a previous CLT test run leaves behind a web page in the IE cache; this leads to an inaccurate CLT result because the webpage is opened from the IE cache, and not through the leak). You can empty the IE cache from within IE or using a cleaner such as CCleaner.
After doing all of the above, run CLT and see what your score is. Is should be 340/340.