Final answer:
The HR manager at a start-up network engineering firm would be least likely to use campus recruitment as a recruiting method.
Step-by-step explanation:
The HR manager at a start-up network engineering firm would be least likely to use campus recruitment as a recruiting method to hire new engineers. Campus recruitment typically involves visiting colleges and universities to attract and hire recent graduates or students nearing graduation. Since a start-up may have limited resources and time constraints, they may prioritize other methods like job boards, employee referrals, and social media to quickly fill the positions.