mate use the monitoring tool it helps to monitoring uncharacteristic website and low quality domainsHow to protect any website for the Negative Seo Attack
You can't, and you won't have to unless you're in the most competitive of competitive markets (payday loans, I'm looking at you).
If you're building a white hat site and have a huge amount of natural links, negative SEO won't work anyway.
If you're building a white hat site and have a huge amount of natural links, negative SEO won't work anyway.