The best certification for Duc would likely be the Spring Professional certification. This certification demonstrates expertise in Java and the Spring Framework, which is widely used in enterprise Java applications. Having this certification would showcase his knowledge and skills in Java development, making it a valuable addition to his resume. The other certifications mentioned, such as CompTIA A+, Certified Information Systems Security Professional, and CompTIA Network+, are more focused on computer hardware, security, and networking, respectively, which may not be directly relevant to Duc's goal of showcasing his Java programming skills.
