Alright, so you’ve dipped your toes in the Red Hat ecosystem and you’ve been studying (at least, I hope you have!) You’ve probably learned a lot of great ways to do things and are possibly gearing up to take the RHCSA. Let’s discuss a few things that may help when the test comes around. Please keep in mind, the NDA for Red Hat exams are no joke, so I will be adhering to that throughout this article.
What you’ll have to work with
After you’ve signed in and you’ve been admitted to the testing room, you will be presented with a terminal. This isn’t just any terminal, this terminal has a camera and microphone integrated into it that will record your every move and breath. Keep this in mind as you’re taking the exam and try to withhold any “salty” comments you may have related to the exam! This terminal will have a RHEL 7 installation on it with a GUI installed. You will be given a VM to access. This VM is where you will be performing the majority of your tasks, which are presented on the terminal as well. Ensure you read all of the tasks before you begin! This is very important! Some of the tasks you encounter may be related to other tasks and, if you do them in order, may conflict and cause issues.
Ok, so now that we’ve discussed your environment (all of which has been detailed by Red Hat in various public posts), let’s talk a little bit about the objectives and some tips that may assist in accomplishing them.
As of June 2018, the objectives are as follows from the official Red Hat website:
- Understand and use essential tools
- Operate running systems
- Configure local storage
- Create and configure file systems
- Deploy, configure, and maintain systems
- Manage users and groups
- Manage security
I’m going to go through these one-by-one and just provide a little insight or tips that may help with possible permutations you may encounter on the exam.
Understand and use essential tools
As shown on the official objectives page linked above, understanding and using essential tools can include grep, redirecting output to files, compressing these files, modifying permissions, and so on. A lot of these should be second nature by now, but keep in mind that the exam is very unforgiving. If you do something incorrectly, your intention is not taken into consideration. If you accidentally mistype something, such as a permission, or grep an extra character, you will miss that objective. With the relatively small number of tasks, missing an entire task can be very detrimental to your score. You will also be under a lot of pressure as the RHCSA is not a cheap exam!
What I recommend is that you install the ‘Server with GUI’ group install when you start your exam in order to make double checking for mistakes much easier! This does take a while, but if you do it first thing while reading your tasks, you won’t waste much time and it will make some of the tasks a lot easier! Especially the simple tasks!
Operate running systems
The “operate running systems” objective is one that contains some potential tasks that can make or break your exam! The RHCSA will fail you automatically if your environment is unable to boot. Yes, you read that right, if your system does not boot correctly for the exam grader, you will receive a score of “0/300”. It doesn’t matter if you did everything else right, you will still receive a “0”.
Due to this fact, when you are performing any type of system target manipulation or other work that involves grub, ensure you reboot your system and test! If your system does not reboot properly, you can ask the exam proctor to reset your VM to its initial state. Do be aware that this will overwrite any work you have already completed, so I recommend you perform any actions that could potentially fail after reboot first. This way, if something goes wrong or you mistype something, you don’t lose a significant amount of work!
Another point to remember is that Red Hat can throw in some pretty hefty surprises. When you access your VM, there may be issues that have to be resolved before you can even continue into the environment. Keep this in mind and study the objectives very carefully! The Linux Academy hands-on labs are crucial in preparing you for these potential surprises.
Create and Configure Filesystems/Configure Local Storage
I have combined these two objectives since they are fairly similar and rely on each other. These tasks can involve LVM, Swap, fstab, different filesystems, resizing filesystems, and other potential tasks. Practice these very carefully! I also recommend doing these tasks first as they can cause your system not to boot. If you perform them last and have an error, you risk losing all of your work performed before them!
Another thing to look out for in the configuring local storage objective is the order of the tasks. There are many ways to perform most tasks on the RHCSA, and if you perform one local storage task a certain way, you might find that a task that comes after it cannot be performed due to space concerns. Ensure you have read all the tasks before you start performing them. Again, a great time to read all tasks is when installing the GUI.
Finally, I know I’ve said it before, but I’ll say it again: REBOOT! Always reboot after performing tasks that could damage the filesystem or cause the root filesystem not to boot! Another aspect of these objectives that could potentially show up is configuring ACLs. This is pretty straightforward, but do go through the Linux Academy labs to ensure you know them very well. This is another instance where having the GUI installed can be very helpful.
Deploy Configure and Maintain Systems
This objective has a significant number of potential tasks you may see. One thing that is very critical to focus on is the “Install and update software packages from Red Hat Network, a remote repository, or from the local file system” section. Although tasks can and very well may show up that contain other aspects of this objective, not being able to access a remote repository can lead to a potential instant fail! Multiple tasks could depend on this single tasks, so make sure you are very skilled at accessing remote repositories, adding new repositories to yum, and other tasks that relate to these operations.
And also, once again, reboot after anything that involves grub, kernel modifications, or the filesystem!
Manage Users and Groups
I’m not going to go too deep into this objective as the tasks that could stem from it are pretty self-explanatory. Ensure you read very carefully, understand sticky-bits and how to set and read permissions, primary groups vs. supplemental groups, and use the GUI to your advantage to check your work!
Ah, security, everyone’s favorite topic! First things first, yes, you should know SELinux. I do have a fun little tip that made things a lot easier for me and it may help you as well! It’s the “-e” flag. The “-e”, or “–equal”, can make mirroring context to a new folder much easier.
Let’s say you want to move the default Apache directory to “/var/web” instead of “/var/www/html”. Typically, you would need to find the proper context for “/var/www/” and add it to the “/var/web” folder. Although this isn’t difficult, it does take some time.
With the “-e” flag, you can simply copy the context from “/var/www/html” to “/var/web” with one line! Isn’t that great?!
To do this, the full command is:semanage fcontext -a -e /var/www/ /var/web
Also, don’t forget to performrestorecon -Rv /var/web to make it effective!
On top of SELinux, you may encounter some Firewall tasks as well as SSH tasks. Since this is an exam, keep in mind that speed is important. Sure, you can diagnose firewall/SELinux issues using logs, but it’s usually just easier to:
- Disable SELinux/Firewall
- Check to see if the problem is resolved
By using this method, you can verify the problem and fix it quickly without rummaging through logs. This is certainly not something you would do in production, but on an exam, take advantage of the faster workflow if it works for you. And, again, use the GUI to your advantage! The GUI has some very simple firewall tools to make your life easier.
The RHCSA exam is certainly not easy! It is a daunting exam that can break the spirits of people who have been in the industry for a long time. Don’t let this discourage you! Good luck! And don’t forget to reboot at the end of your test!
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