Kirlyam is a security administrator seeking the best way to defend her organization's network against sniffing. What is the BEST way for her to accomplish this?

Domain 4: Communication and Network Security Practice Questions
Questions from the following topics are included in this domain:   
Assess secure network design principles.   
Implement secure network design principles.  
Secure network components using network access control devices.   
Implement secure design communication channels.  
Understand data communications and virtualized networks.