Currently there are three major organizations which seek to provide Linux Certification exams :
Linux Professional Institute
In general our bias is towards the certifications offered through the Linux Professional Institute (LPI). LPI is a non-profit organization, which has used volunteers to develop itself as a community project mirroring the development of Linux itself. Linux enthusiasts have volunteered for LPI for tasks ranging from taking care of its booth in trade-shows all the way to preparing examination questions. LPI now has sponsor organizations as well as paid officials, but is still deemed to be an unbiased organization dedicated to creating the best and standardized Linux Certification. LPI currently offers two levels of certification. Each level of certification consists of two exams. Candidates have to be LPIC Level 1 certified, before getting LPIC Level 2 certification.
Linux+ is the latest certification program offered by CompTIA, the creators of A+ certification. Linux+ is also a vendor-neutral certification aimed at entry level Linux professionals. There is significant overlap between Linux+ and LPI level 1 exams. But LPI's focus is certification for system administration whereas CompTIA's focus is towards help desk personnel.
Red Hat is the only major distribution vendor which is currently providing a certification for its own distribution. Other major vendors like SuSE, Turbo Linux and Caldera seem to have put full support behind LPI. In general we prefer distribution independent certification, but there could be some valid reasons to consider Red Hat certification as well. If your organization (current or prospective) predominantly uses Red Hat distribution, becoming a Red Hat Certification Engineer may be more relevant.
To prepare for Linux certification examination
and to get hands-on experience with various aspects of Linux, click