CompTIA Linux+ and the RedHat Linux certifications are the two leading Linux administrator certifications the employers look for. While RedHat certifications are centered around RedHat Linux servers, CompTIA Linux+ is a vendor-neutral certification. CompTIA+ covers most popular server distributions like RedHat, Debian, Ubuntu, and SUSE.

CompTIA Linux+ certification is comprised of two examinations:

1. CompTIA Linux Certification (LX0-103) – The LX0-103 covers the below domains:

System Architecture
Linux Installation, and Package Management
GNU and Unix Commands
Devices, Linux Filesystems, Filesystem Hierarchy Standard.

2. CompTIA Linux Certification (LX0-104) – The LX0-104 covers the domains:

Shells, Scripting and Data Management
User Interfaces and Desktops
Administrative Tasks
Essential System Services
Networking Fundamentals
Security

Each exam has 60 multiple choice questions with a 90 minutes time limit. The questions are weight based and the passing score is 500 (on a scale of 200–800).

Note: Candidate must pass both LX0-103 and LX0-104 Exams to complete the Linux + certification

3. Red Hat Certified Engineer (RHCE) Certification - RHCE certification covers the following domains -
System Configuration and Management
Network Services (HTTP/HTTPS, DNS, NFS, SMB, SMTP, SSH, NTP)
Database Services

Red Hat Certified Engineer (RHCE) certification exam consists of 10-15 performance-based tasks with 3.5 hours time limit. The exam is based on real-world problems and costs USD 400 plus tax.

4. Puppet Certification – The Puppet Certification covers the domains:

Language and Study Guide
Modules
Using Puppet
Puppet Internals
Classification
Console
Ecosystem

The puppet certification exam has 60 multiple choice questions with a 90 minutes time limit. It is a computer-based exam and costs USD 200.