In the last installment of my Linux Careers column (LWM, Vol. 2, issue 2) I focused on the quandary posed by certifications: most qualified candidates feel that their experience speaks for itself, but as Linux becomes more prevalent in the corporate environment, more potential employers are looking for certifications as a benchmark of the candidate's knowledge and experience in skill sets relevant to the job at hand. This month, I'll help you to understand which certifications corporations are looking for - and why.

All Linux certifications fall into one of two categories: vendor-neutral and vendor-specific. Vendor-neutral exams include the LPI, CompTIA+, and BrainBench certifications. These exams attempt to set a threshold for general Linux knowledge and test the candidate's ability to answer questions that apply to work within any distribution or environment. LPI does a particularly good job of using information gleaned from Linux professionals to develop exams that are relevant for Linux administrators with particular levels of experience.

Although each company places a different weight on certifications in the candidate screening process, when I talk to companies that are seeking certified people, they usually place the most weight on vendor-specific certifications. The company wants to know that the job candidate not only has the general Linux knowledge to succeed within their organization, but can effectively run their particular vendor's systems. They want a candidate who can fix things when they break without having to learn the ins-and-outs of the system first.

When it comes to vendor-specific certifications for Linux administration, the Red Hat Certified Engineer (RHCE) is the certification to have. There are a number of reasons for this. First of all, Red Hat continues to lead in market share, although Novell is emerging as a strong challenger. It just makes logical sense - if more companies have Red Hat installed and you, as a candidate, want to appeal to the most companies, RHCE may be the stamp you need on your résumé to differentiate yourself and get a foot in the door.

Another reason the RHCE is the front-runner is because Red Hat has taken the exam playing field to a whole new level. A typical certification exam is in an easily scored, multiple-choice format. There are a multitude of prep guides on the market for these exams. Essentially, any person who can memorize the material could pick up a book, read it, and pass the test - without ever touching a computer.

In this regard, the RHCE is very different; although Red Hat certification exams do include a multiple choice section, the RHCE also includes an intensive hands-on segment. The engineer aspiring to become certified must work in a timed lab setting and perform real operations on the Red Hat platform, focusing on server, networking, and security services.

As Bryan Smith, an IT trainer with over 35 different certifications, explains, "There are 'many ways to skin a cat' in system administration. In a lab-based exam, you can do it any way you like. The nice thing about lab-based exams is that they are forgiving if you forget a memorized item or two. If you have the experience, you can get the job done in the time allotted and not get penalized." Many RHCEs explain that the exam is one of the hardest they've ever had to take, mostly due to the level of familiarity with the system required and the strict time limits.

This year, Novell rolled out its Certified Linux Professional exam, which includes a simulation portion. The problem with these simulations, as Smith explains, is that, "If you forget something on a Q&A exam, or a simulation that says 'point to the menu/icon that you use' - there's no forgiving. It's funny, but the reality is the person who crammed for the exam might know more things than an administrator who has years of experience." However, Novell's more complete Certified Linux Engineer exam is a compromise with a virtual lab, which is closer to the real lab included in the RHCE.

Sometimes it's the combination of vendor-neutral and vendor-specific certifications that can demonstrate the candidate's ability best, no matter what company you want to work for. By combining a vendor-neutral certification such as the LPI level 2 with RHCE or another certification with vendor tie-in, you may find that your résumé holds the widest appeal to hiring managers and engineering directors.

Once a Linux candidate is certified, he or she can expect to face a tougher interview. As Todd Cranston-Cuebas, senior technical recruiter for Ticketmaster, told me, "When a certified candidate comes into an interview, we expect that candidate to know the material down cold; we'll drill them on it, because we know they're certified."

That being said, I personally believe that the best indication of a candidate's qualifications for a particular position is his or her experience. Cranston-Cuebas agrees: "When someone who's new to Linux asks me if they should get certified, I tell them that it might be a good idea, but the best thing to do is just jump in and learn the technology."

Many companies that are just now moving to Linux think that certifications are the only real way to prove that a candidate has the skills they're looking for. However, as anyone who works in open source on a regular basis knows, certification programs - especially those that are worth the effort - are relatively new to the market and still changing to meet the needs of both candidates and companies.

Skill in working with open source technologies is primarily proven by what you do with what you know. Adding a relevant certification to the experience you've amassed is a great way to prove that you are committed to advancing your career and willing to go the distance to demonstrate that commitment to potential employers.