Which element of Public Key Infrastructure (PKI) verifies the applicant?

The security administrator of ABC needs to permit Internet traffic in the host 10.0.0.2 and UDP traffic in the host 10.0.0.3. He also needs to permit all FTP traffic to the rest of the network and deny all other traffic. After he applied his ACL configuration in the router, nobody can access to the ftp, and the permitted hosts cannot access the Internet.
According to the next configuration, what is happening in the network?

A security analyst in an insurance company is assigned to test a new web application that will be used by clients to help them choose and apply for an insurance plan. The analyst discovers that the application is developed in ASP scripting language and it uses MSSQL as a database backend. The analyst locates the application's search form and introduces the following code in the search input field:

When the analyst submits the form, the browser returns a pop-up window that says "Vulnerable".
Which web applications vulnerability did the analyst discover?

A security consultant decides to use multiple layers of anti-virus defense, such as end user desktop anti-virus and E-mail gateway. This approach can be used to mitigate which kind of attack?

You have the SOA presented below in your Zone.
Your secondary servers have not been able to contact your primary server to synchronize information. How long will the secondary servers attempt to contact the primary server before it considers that zone is dead and stops responding to queries?
collegae.edu.SOA, cikkye.edu ipad.college.edu. (200302028 3600 3600 604800 3600)