SEO crawler DDOSing sites

Question

i run 36 websites which have thousands of pages  thge site is configured to cache on access using standard in-memory caching  ASP.NET 4.6  after some digging into  IIS logd i am using an SEO bot tool, SEMrush, which essentially triggers a denial of service attack against the sites because of simultaneous requests for the 'long tail' of pages which are never viewed by a user and hence aren't stored in the cache.

Answer 1

The 3 solutions you have are pretty much good and there isnt any other options to go with. I have researched and havent found any other solutions