Which of the following is BEST at blocking attacks and providing security at layer 7 of the OSI
model?

A.
WAF

B.
NIDS

C.
Routers

D.
Switches

Explanation:
A web application firewall (WAF) is an appliance, server plugin, or filter that applies a set of rules
to an HTTP conversation. Generally, these rules cover common attacks such as cross-site

scripting (XSS) and SQL injection. By customizing the rules to your application, many attacks can
be identified and blocked. The effort to perform this customization can be significant and needs to
be maintained as the application is modified.
As the protocols used to access a web server (typically HTTP and HTTPS) run in layer 7 of the
OSI model, then web application firewall (WAF) is the correct answer.