If I am manufacturing 5 products ,so for better marketing to have 5 website like a.com ,b.com, etc. pls reply?

[Peter]

Answer is Yes and No. Let me explain.

If your products are in same category answer is yes. Building online presence is much easier if you manage one website. All links should be natural and you will keep users engaged with other products.

The problem happen if your products are in different industry. For example Hewlett-Packard also build medical equipment, but you can't find this on their website. The company was split and HP medical is now even with different name. It's some kind unserious if you build computers, printers and medical equipment.

That's why everything dependent from your products and you should get advise from someone that is qualified in brand and product management.