I have static IP for my computer provided by the ISP. If I want to build backlinks for my 2 websites, can I start of building backlinks from the same system for 2 websites or I have to use the Proxy server or some others for each one. Different IP address means, Is it from various IP addresses provided by the ISP provider? Or Is it for the domains located on various servers? Could you please clarify the same.
I'd use a proxy server or a VPN like Hide My Ass. The biggest issue is that you'll get your IP addressed banned if you're not careful and then your ISP will be very unhappy with you.
Ofcourse you can do building backlinks from the same system but the 2 websites must not be the same or the content it in must be unique. And you must be very careful in building backlinks that the keywords you are targeting must describe your website and the meta tag you provide must be very informative and carry your keywords in it.
Option 2, it has nothing to do with your ISP. Let say I own 20 domains and they're all on the same IPs. Then I sell a link on each domain, you will get 20 links from domain on same IPs. Then Google will see that the links come from the same IPs and won't add positive value to your links.