Red Hat: Red Hat Certified System Administrator (RHCSA) and Red Hat Certified Engineer/ (RHCE), launched January, 1999
Red Hat launched its certification program in January 1999 with the high-level Red Hat Certified Engineer (RHCE) designation. In November 2002, the entry-level level Red Hat Certified Technician (RHCT) title was added. With the release of the version RHEL6, the RHCT title was renamed RHCSA, Red Hat Certified System Administrator
RHCE is for advanced system administrators who have quite a bit of experience to draw upon. To earn the RHCE certification you must pass a full day hands-on lab exam consisting of three elements: a written test, a server install and network services configuration lab, and a diagnostics and troubleshooting lab. The test is administered at a Red Hat facility. This is the most well-known advanced Linux certification currently available.
Red Hat Certified Architect (RHCA) launched in 2005
RHCA is the designation Red Hat calls its “capstone” certification, and it includes planning and designing and managing an open source infrastructure in large and complex environments. The RHCA certification can be earned by an RHCE after completing any five Certifications of Expertise (CoE)
Red Hat Certification are the most popular and sought after Linux Certification as Red Hat Enterprise Linux is the most widely used Linux Distribution.
CompTIA, which administers the Linux+ certification, is well-known for its slate of vendor-neutral foundation-level certifications. Linux+ is a basic, entry-level certification for Linux system administrators. Although initially created for technicians with six-months of experience installing, operating and maintaining Linux operating systems, the latest version of this certification suggests that 2 years or more experience is more appropriate. To achieve Linux+ certification, candidates must pass two exams consisting of 60 questions each. The exams cover system architecture; Linux installation and package management; GNU and Unix commands; devices; Linux filesystems; and the Filesystem Hierarchy Standard. This certification is not linked to any specific distribution of Linux.
In 2010, when an updated version of this certification was released that changed the number of required exams from one to two, the name was also changed to Linux+, Powered by LPI. LPI is the acronym for the Linux Professional Institute, which also offers a Linux certification program that is described below. CompTIA recommends Linux+ as a stepping stone to vendor-specific Linux certifications such as Oracle Certified Associate and Novell Linux certifications. It is also a good certification to use as a learning map if you are new to Linux and need to identify the skills that you need to grasp to be an effective Linux system administrator.
LPI: Linux Professional Institute Certified (LPIC) (launched January, 2000)
LPI is a non-profit organization that advocates and assists in the professional use of Linux, open source, and free software. The vendor-neutral LPIC program is three tiered, with each tier requiring passage of two exams. Level 1 (LPIC1) is for junior level administrators. Individuals must achieve level 1 (LPIC1) certification before attempting level 2 (LPIC2), the intermediate level designation. The top level is level 3 (LPIC3).
SUSE Linux certification
Becoming a SUSE Certified Engineer covers the skills needed to perform tasks on Storage Solutions (SCE in Enterprise Storage), Linux (SCE in Enterprise Linux), and Systems Management (SCE in Systems Management) platforms.