最佳答案
Now that SSL 3 has been found to be vulnerable to the POODLE attack:
Which versions of SSL/TLS does System.Net.WebRequest use when connecting to any https Uri?
I use WebRequest to connect to several 3rd party API's. One of these has now said they will block any request that uses SSL 3. But WebRequest is part of the .Net core framework (using 4.5) so it is not obvious what version it uses.