Dear Mridul;

I think that the most important point to verify journal validity is the database that journal was indexed.

for example, the best way is search the name of journal in the "Master Journal List" in Thomson Reuters web site.

All the journals that index in Master Journal List is valid and have highest quality.

please search the journal name in the below address.

http://ip-science.thomsonreuters.com/mjl/

In a fake journal what points inform me it as fake ?

I agree with Mr Saman Lashkari.,

in Iran we test our \valid journals in this way.

Best wishes. in the other hand you have to know your valid journals in your research Area. 

Thank you all

Please have a look at the list here: https://scholarlyoa.com/

We call it  "Beall's List of Predatory Journals"

Good idea,