Computer Science homework help

Answer the four questions noted below.  Please use at least one reference and ensure it’s in APA format (as well as the in-text citation).  Also, ensure to NOT COPY DIRECTLY from any source (student or online source), rather rephrase the author’s work and use in-text citations were necessary.
Describe the CIA triad and the defense in depth principle? Why are those concepts important when designing your network security strategy?
What are the steps for an incident response plan? How does network security play into an incident response plan?
What are some major differences between open source and commercial\closed source software and solutions? Should you consider one over the other?
What are firewalls? What are VPNs? What are some alternatives to a traditional firewall? What are some alternatives to traditional VPNs? How does the alternatives improve the traditional version of both?
Note: The essay should include an APA cover page and at least two references (academic or professional literature) in APA v7 format.