suppose my website is under Denial of Service (DoS) attack, then what will Google think about it - whether the site is under DoS attack and therefore the traffic has unexpectedly increased or the webmaster is using some kind of wrong method to provide auto hits to the website?
search "Denial of Service (DoS) attack" and see there are so many sites related Denial of Service (DoS) attack. so you just think about that they mention Denial of Service (DoS) attack then after they get good serp so we can judge that google never think about wrong for this thing.
writing about DoS attack is one thing and experiencing it is another. i think you are on the wrong track
How on earth will google know you are experiencing a DoS attack, unless you are using google analytics. It is very unlikely that the perpetrators of the said DoS attacks are using google serps to redirect the attacks to your site. What do you mean ???