Red Hat Enterprise Linux (RHEL) is the most popular Linux distribution amongst medium to large enterprises, and Red Hat have developed their own training courses and certifications to ensure that professional standards are high.
There are three levels of certification provided by RedHat - RHCT (Red Hat Certified Technician), RHCE (Red Hat Certified Engineer) and RHCA (Red Hat Certified Architect).
RHCT is the entry-level certification, suitable for a junior-level system administrator looking after Linux systems. Topics covered include package management, network configuration, file system administration and basic system troubleshooting.
RHCE is a well respected qualification, which shows a good level of knowledge of use and troubleshooting of Red Hat Enterprise. Topics covered include advanced package management, system services, kernel configuration, network configuration, advanced account management, web services, mail services, virtualization, NFS and troubleshooting.
RHCA is a very difficult to attain qualification, currently held by less than 1000 people worldwide. To attain the RHCA qualification, one must pass a total of six exams - the RCHE exam; RedHat Enterprise Security: Network Services, RedHat Enerprise Deployment, Virtualization and Systems Management; RedHat Directory Services and Authentication; RedHat Enterprise Clustering and Storage Management; and RedHat Enterprise Systems Monitoring and Performance Tuning Expertise. Those who attain RHCA qualification can expect to find themselves in high demand, and command a sizeable salary.
For those unfamiliar with Linux, the RHCT is a good initial goal to aim for. RHCT certification provides a good 'foot in the door' for would-be employees looking to impress an employer and gain their first Linux System Administration job.
For those looking to run an entire network, RHCE certification should be sought. The RHCE course provides a good level of knowledge, enough to be able to cope with most challenges day-to-day administration can throw at them. The RHCE exam proves a high level of knowledge, and is a highly respected qualification.
RHCA certification should only be pursued by those hoping to forge a career as a professional Linux consultant and/or troubleshooter. Together, the examinations that make up the certification represent more than 30 hours of test time - to say nothing of the preparation time required. As such, RHCA certification is only for the most dedicated and studious of people.