Yes you are right .html is not necessary but i have implemented it so i
don't want to change it.
I have make the unique url for every product with .html extension
I think this is the main for SEO.
Now I want to ask that if I want to pass query string with this unique url
for SEO than should I use "?" for query string or I should use "/" .
which is right from below url:
Please suggest me.
Great, no problem.
It was difficult to find where the issue is because I didn't know that
you've modified the IIS settings.
BTW, I don't think that replacement of "aspx" to "html" will give you
a big advantage in SEO. I think, Google and others don't rely on this
at all and an extension has no effect on rankings. Read what Google
said about this