Linux Kernel

Linux Hardware and Software Layers

There are four main layers with Linux which are monolithic and are tied into the one system. The base layer is the hardware which can talk through the kernel, using it to interact through drivers for the software to function. The next layer is the kernel which acts as a bridge between the hardware and the software.

The next layer of this Linux hardware and software stack is the Shell which is normally Bash. This is where the Command Line Interface (CLI) commands are used and talk through to the kernel to manage the hardware. The top layer is the user interface where the user uses the Graphical User Interface (GUI) for things like web browsers and text editors.

Linux is Monolithic

The way that Linux is monolithic is tied to its architecture. This architecture is designed to have all core services run together as a group in a Kernel Space. This Kernel Space is something that is a privileged and highly secure area of memory. This design is making Linux fast and efficient based on lower delays between core services.

The other type of kernel is called the Microkernel which uses a user space on certain operating systems like Minix 3 or the Apple IOS which uses XNU that is more of a hybrid kernel. X not Unix (XNU) is a specialized hybrid monolithic and microkernel that is used by Apple to provide the benefits of both types of kernels.

Four Main Jobs of the Kernel

These are managing device drivers, system calls, process management, and memory management. Device drivers are the actual assembly code for each of the items of hardware that talk between the hardware and the kernel. System calls are the actual requests from software to specific hardware for things like writing data to the disk.

Process management is where the kernel decides what process gets run and how long it can be in the CPU. The memory management function of a kernel is where the kernel decides how much RAM and for how long it stays in memory. The kernel has more functions like preventing and mitigating conflicts in processes and acting like a superuser to manage security and resources needed to perform tasks.

Conclusion

The kernel is a concept that doesn’t get talked about enough. This concept of a kernel is the essence of Linux which in reality is more a kernel than an operating system. You can get more in depth into this topic by including them in your studies. Studying has saved me more time on certification exams and will be something that will allow me to remain consistent. Study well guys and be a lifelong learner.

Information Technology Roadmap

Information Technology Roadmap

There are some aspects of information technology that are more relevant for building a career roadmap. Depending on how you want to go about it you can tailor your roadmap to the IT career that you want to be in. This roadmap will help guide you in your career. When setting up a roadmap there are things that you will want to do like getting a broad IT skill set that will help you in your career.

Roadmap

The way that I went about it was to do the CompTIA ITF+ and then the A+ was next. The things that I was doing would correlate with the Tech+ and the current version of the CompTIA A+ exam. I would also recommend putting in at least one cloud certification like the AWS Certified Cloud Practitioner or the AZ-900.

I did this to understand more about the underlying technology in hardware and software components of PCs. This has helped develop more skills as I now hold ten certifications in IT. The path that I am taking was thought out more along the fundamental pathways for Azure, AWS, Linux, and Cisco certifications.

My Own Roadmap

I want to be able to help guide your journey and allow you to see how I am going about my own roadmap. You don’t necessarily need to have ten certifications, but you would need both skills and certifications. The reason that I am going about doing these certifications is so that I can tailor my roadmap more towards a CIO, CTO or CISO job role which is something that would need deep technical knowledge.

One of the things that I am doing is focusing more on the Cisco and Microsoft technologies before other certification paths. This will be something that can help with Cloud Networking and Network Security which are two of the subjects that I am pursuing. Later on I might do Network Forensics but want to save that for future studies.

Building Your Roadmap

For your own roadmap, I would recommend that you start with the fundamentals and get a wider view of Information Technology. This should be before you decide what skills and certifications you would need to have on your own roadmap. Going broadly in IT has helped my own business as I can do more roles as needed and understand the technical side of my content writing business.

Conclusion

Giving something back is what the next part of my journey is about. This advice to tailor your own career by tailoring your roadmap will help in your career journey and future in IT. By taking the time to understand and plan what you want to do with your career you can gather the skills and certifications needed for your career.

History of Linux and FOSS

 History of Linux

For the history of Linux, it is best to understand more about Unix. Unix was made in 1969 by Bell Labs by Ken Thompson and Dennis Ritchie. It was intended to be a multi-user system and was rewritten with C in 1973 for portability. Unix was released to the public by Bell Labs with Version 6 in 1975 for general use. 

In 1983, Robert Stallman created the GNU Project to create a free Unix- like system which is something that Linux eventually evolved from. Linus Torvalds started Linux as a personal hobby project back in 1991. This was a similar model to the GNU Project and was licensed under the GNU General Public License.

In 1992, the GNU Project and the Linux Kernel were merged under the GNU GPL which allowed for an open-source version of Linux. There are different distributions that came out like Debian and Slackware in 1993 allowing for more distributions and flavors later on. There are three main distributions today that most Linux systems are derived from. They include Debian, Red Hat and Arch Linux mainly, which are where the different flavors originate from.

History of FOSS

FOSS is something that grew out of the general cooperation of building software in the 1960’s and 1970’s. It was built on the concept of free software which Robert Stallman’s GNU Project and Free Software Foundation helped with the development of Free and Open-Source Software later on using Linux and other distributions. The Free Software Foundation was made in 1985 by Robert Stallman.

In 1998, the term open-source was coined by the Open-Source Initiative which helped the development of different companies and organizations contributing to other open-source projects in the corporate world. This is something that is happening still today. Linux is used heavily in web servers, cloud computing and in mobile devices like Android.

Knowledge Byte

The history of Linux is something that I have studied for in college and also when studying for the LPI Linux Essentials certification that I have. There are some ways to study for the Linux Essentials which include a study plan, having three or more resources and also keeping a schedule of each section that you have selected for your study sessions. It is also good practice to eat healthier and get enough sleep, so you are not having issues with energy or your mental health.

Conclusion

These are some of the events that contributed to Linux and FOSS. There are companies that continue to contribute to open-source projects like Git and Apache Server. The development of more distributions and flavors is getting Linux to be a more portable operating system than Windows. Linux is now used to power corporate systems and supercomputers along with embedded systems.

OSI Model vs. TCP/IP Model

 The OSI Model (Open Systems Interconnection) is essentially a reference model that helps IT technicians understand the different layers. For the TCP/IP Model, this is the Transmission Control Protocol/ Internet Protocol that is a functional model and is how the layers actually work. There are seven OSI layers compared to the four TCP/IP layers. The OSI model was made by the International Organization for Standardization as a conceptual model.

OSI Model

The best way to think about the OSI Model is to break it down into layers. These are from the bottom to the top and starts with layer 1 which is the Physical layer, layer two is the Data Link layer, the Network layer, Transport layer, Session, Presentation and layer 7 which is the Application layer. By using the Please Do Not Throw Sausage Pizza Away mnemonic you can remember these layers.

The Physical layer is the actual hardware, cabling, and wireless mediums and uses encapsulation to go to the Data Link layer which are frames. The Network layer uses packets and encapsulates the frames into packets. By the fourth layer, the Transport layer, the packets are encapsulated by ports.

With the Session layer, the ports are encapsulated by sessions which interact with layer six to allow for encryption and then the Application layer which is by that point data. By understanding these layers, you can understand more about what the TCP/IP Model is about and why it is easier to troubleshoot with the OSI model. The OSI model is also used by vendors that create hardware and software to be interoperable.

TCP/IP Model

In the TCP/IP Model there are four layers which are the Network Access layer that corresponds to Layer 1 and 2 of the OSI Model, the Internet layer for Layer 3, Transport layer for layer 4, and the Application layer which corresponds with layers 5, 6, and 7 of the OSI Model. This model was developed by the Department of Defense and is a practical standard for internet communications.

Conclusion

By learning more about the OSI and TCP/IP models you can understand how to troubleshoot more effectively. There are some encapsulation and decapsulation items going up and down the TCP/IP stack at the same time. This allows for effective communication across systems. When you understand this at a deeper level you can go for more advanced certifications like the CCNP or even the CCNA.

NAT Types

 Network Address Translation

There are three different types of NAT which are Static NAT, Dynamic NAT, and also Port-Address Translation which is also known as NAT Overload. Static NAT is a one-to-one mapping of an internal private address into a public address. These types of NAT are some of the main types and there are some others like gaming types of NAT that I will not go over in this blog post.

Dynamic NAT is a one-to-many mapping with one private address and many public addresses. The Port Address Translation is used with a single public address and multiple private addresses. PAT, also known as NAT overload, is used mostly by home routers and is the most common type. PAT is done using port numbers for each session that is connected by each IP address.

Static and Dynamic NAT

The static NAT type is used mostly by people hosting a server in a private network behind a firewall or router. The dynamic NAT type of Network Address Translation is used by companies to map their IP addresses. This results in a one private IP to multiple public IP addresses. This is most commonly done by companies with larger networks.

Knowledge Byte

There are some things to work on regarding computer networking certifications. The certifications that this will help with the most are the CCST Networking and the Network+ certification. Certification study is one of the best things that you can do for your career and will help you get better jobs over time along with some education.

In order to understand a book or course you would want to section off the information in a study plan and be consistent in order to finish the study plan before taking one of these exams. With a study plan there is built in consistency, and you will want to keep pace with your study sessions. This is in order to pass the exam or class that you are in. If you stick to your plan, you can make it better or do better things with it next time.

Conclusion

These types of NAT are the main types and will help you out on exam day if you can put in a solid study plan along with some reading. I do have the CCST Networking and the CCNA along with other certifications and this information has helped me with those exams. When working on a study plan it should include some reading, practice, and thorough online course study.

RAID Types and Uses

There are different types of RAID which is Redundant Array of Inexpensive Discs. The more common ones include RAID 0, which is striping, RAID 1 which is mirroring, RAID 5 which is distributed parity, and RAID 6 which is dual parity. There are also combinations including RAID 10, RAID 50, and RAID 60. More combinations are used, however RAID 2, 3, and 4 are considered obsolete in favor of RAID 5 and 6.

RAID 0

RAID 0 is also called striping and is where data can be split between drives and can improve Read/ Write functionality. This provides better performance. This is something that doesn’t have redundancy just better read/ write speeds for things like cache or temporary data.

RAID 1

RAID 1 is mirroring which allows for some redundancy and clones the data providing higher levels of redundancy. There are some things that it works best on like databases, and critical drives. With a minimum of two drives needed it provides the highest security of critical systems. Although there is a reduction of 50% storage capacity.

RAID 5

This RAID is used for distributed parity where the data is in a good amount of speed and storage capability. The best use for this is for file servers and any storage that is needed. With three drives needed at a minimum there is an allowance of 1 drive failure that can be tolerated. This provides the best balance of any RAID type. 

RAID 6

RAID 6 is also known as double parity where there are four minimum disks that can be used for RAID 6. This improves on the RAID 5 and is used more for higher protection on larger systems. There are two failures allowed on this RAID type.

RAID 10, RAID 50, and RAID 60

The RAID 10 type has been done mainly for both the striping and mirroring capabilities, high performance and high redundancy. This is helpful for enterprise databases and servers. RAID 50 and 60 are both used to provide high performance and either distributed parity or double parity.

Conclusion

Using RAID is something that you will learn in the A+ exam training materials and is for the computer hardware and virtualization modules. Choosing your RAID type is something that is per the situation that the company has and the policies for choosing the RAID level. It is also what is best for the equipment. The main thing is remembering the different types of RAID and what situations they are used for.

Cloud Concepts

 Cloud Concepts

There are three main types of cloud computing services. These are IaaS, PaaS, and SaaS which are Infrastructure as a Service, Platform as a Service, and Software as a Service. There are also different types of cloud computing platforms. These platforms are generally put into Private Cloud, Public Cloud, Community Cloud, Hybrid Cloud and Multi-Cloud types.

IaaS, PaaS and SaaS

Infrastructure as a Service is characterized as the service for people who want to control their operating system, applications, security, and any data that they have while letting the cloud provider handle all of the physical security, firmware updates, networking and cabling and things like that. Platform as a Service is used generally for an application development platform provided by a cloud provider.

In a PaaS solution, the cloud provider handles the operating system, operating system patches, security issues and all of the IaaS components that are below the operating system. This essentially leaves the application, application security, and data up to the developer. In a SaaS environment, there is essentially everything except for the data and some application security issues that the cloud provider takes care of.

Cloud Platform Types

Private Cloud is a type of cloud platform where the company owns the cloud infrastructure and hosts an internal cloud that is private. Public Cloud is where a company has infrastructure and services on a public cloud service provider like AWS, Azure or GCP. In a public cloud the infrastructure is shared with multiple tenants.

Community Cloud is where there is an industry or some common community of companies that use cloud infrastructure or services. Hybrid Cloud is a cloud platform type that uses more than one type of cloud platform like public and private cloud. The multi-cloud is where there are two or more cloud providers or cloud platform types available.

Conclusion

Knowing how the cloud is structured will help you with your studies of cloud computing. There are multiple cloud providers like Amazon Web Services, Microsoft Azure and Google Cloud Platform. Knowing more about them can help in getting certain cloud certifications like the AZ-900 or the AWS Certified Cloud Practitioner certifications.

These cloud concepts can help on any cloud related certification exam. The way that you can calm some of the anxiety around studying for certification exams is by knowing the material through diligent and consistent practice. Other things like diet, exercise and sleep play a role in the study plan completion. I currently hold the AZ-900 exam and am going for my AWS Certified Cloud Practitioner certification later in March 2026. This will be my tenth IT certification, so I am excited about it. Use the certifications that you want to go for as steppingstones on the way to your career goals.

Linux CLI Commands

 Linux CLI Commands

When using Linux there are some basic Command Line Commands that are used for various functions in Linux. There are some basic commands including ls, cp, mv, and cd. Other commands that are helpful include grep and man that get data by searching for the string in a file. The command man is short for manual pages; this gives information about most commands. 

The command ls stands for list directory and can be used with flags like the -la which allows for a long listing format and shows all files and folders in the directory. When using the cp command, you can copy a file or folder into another directory or copy a file in the same directory. With the mv command you can move a file or folder from one directory to another. The cd command is for changing the directory that you are in.

Basic Commands

There are other Linux CLI commands like pwd, whoami, and ifconfig that show the present working directory, what the current user is, and the network interface configuration of the device which includes IP addresses. Some of the other basic Linux commands include mkdir that makes directories and touch which makes empty files. These three commands are used more in cybersecurity instances but remain essential to anyone that wants to learn Linux.

Display Commands

Commands in Linux also include cat, head, tail, more and less. When using the command cat you can display files content. It is the same when using head and tail which show the beginning of a file or the end of a file. The commands more and less are used to go through pages on long files with less being more with better functionality.

Conclusion

There are more commands, but these will help you for the most part. There are some commands like rm and sudo that need to be used with caution; however, you can look them up along with other Linux commands. Using Command Line Interface commands on Linux devices is something that you will have to work on to get better at.

Each of these commands can be used with modifiers or flags and are sometimes similar so look them up with the man pages to get more familiar with them. There are two other commands that can be used which are help and info which are similar to man. There are additional commands that can be used, however getting more repetition is something that you will need to work on.

DNS and DHCP

DNS and DHCP

DNS is an acronym for Domain Name System which is a way for a computer to convert names to IP addresses. Domain Name System uses port 53 and is a protocol that uses both TCP and UDP. Dynamic Host Configuration Protocol or DHCP is used to set up pools of addresses to dynamically assign IP addresses to hosts on a network. Unless Static IPs are set by an administrator the network functions better using dynamic addressing.

DHCP can assign IP address, subnet mask and default gateway network configurations and works with an IP Helper address to get to the DHCP server. This allows IT teams to configure things like VLANs and allow for an IP Helper to denote the DHCP server on the switch or router. DNS allows the naming of websites to function instead of using IP addresses to go to websites and is more distributed.

DNS

Using TCP and UDP allows DNS to have a faster by default and more lightweight use using UDP and a more secure or larger packet use when needed for TCP. DNS allows for the use of Top-Level Domains, also known as TLDs, that are like the .com or .net domains. Domain Name System uses caches with root servers that are the TLD servers and act essentially as a decentralized name lookup service.

DHCP

DHCP uses UDP ports 67 and 68 using port 67 for the DHCP Server and 68 for clients. This allows for faster and connectionless communication over UDP compared to TCP. DHCP uses the Discover, Offer, Request, and Acknowledge process which is referred to as the DORA process.

Dynamic Host Configuration Protocol uses APIPA (Automatic Private IP Addressing) to address clients that for some reason fail to get an IP address. This APIPA address starts with a 169.254.x.x IP address and can be a DHCP server failure or a duplicate IP address.

Knowledge Byte

Performance based questions are often not addressed in textbooks. These gaps are addressed in doing labs and in a work or lab environment that can help with the application of theory. This is something that you should take care of in your studies because you will be asked PBQ questions on some IT certification exams.

Conclusion

DNS and DHCP are often covered in Information Technology certifications and are both essential. DHCP is used mainly in places where larger amounts of computers are in a small business or enterprise environment. Performance-based questions can be easily overcome with labs, practice or on the job training.

There are some things that you can do with DNS and DHCP that will allow you to expand your skill set like learning the difference between an A record AAAA record, MX record, and a CNAME record. For DHCP learning more with the DORA process will be beneficial with tools like Wireshark.

Types of Motherboards

Motherboards

There are three main types of motherboards, which include ATX, Micro-ATX, and Mini-ITX, that are common in desktop computers today. The ATX is a form factor for desktop computers and more advanced gaming setups, ATX also supports more expansion slots. Micro-ATX is more for moderate desktop builds and can fit both ATX and Micro-ATX form factor cases. The Mini-ITX form factor is for Mini-PCs and for home theater builds.

Some of the other form factors for motherboards include ITX which is more of a historical or older type of motherboard. In addition, the E-ATX or extended ATX are more for the larger computers like high-end workstations and enthusiast builds. There are also other types of motherboards like laptop embedded motherboards, an older standard called BTX that is obsolete now and Nano-ATX or Pico-ATX motherboards that are for industrial or embedded systems.

Motherboard Sizes

There are different sizes for motherboards that include the ATX being 12 x 9.6 inches, Micro-ATX being 9.6 x 9.6 inches and the Mini-ITX being 170 x 170 mm. The E-ATX or extended ATX is up to 12 x 13 inches. There are things to consider when selecting a motherboard type that includes the chipset, the type of processor, the form factor of the case, and how many PCIe, RAM slots and ports are available.

Knowledge Byte

Burnout and Lack of Motivation is something that can happen when studying for certification exams. The best way to get this to work is to do more manageable study periods that don’t include marathon sessions. There is some truth to being consistent in your training and aiming for being 1% better every day.

Putting in the time should not feel boring or tedious. If it is becoming boring or tedious, try another type of training like flash cards or reading a random chapter in the book to liven up your training. There are some things that can help if you feel that you are getting burnt out, these include trying to change your routine to make studying a part of your daily routine.

Conclusion

There are some ways to go about training and if you get to the point that it seems that you are not making any progress then switch up your studies and find something that works for you. Motherboards are something that you can understand that will help you in your IT journey. Knowing this will help understand the fundamentals of Information Technology. There are more things that I will be discussing in the coming weeks on this blog so stay tuned.

RAM, ROM, and NVRAM

 RAM

Random Access Memory is typically used by an application to store temporary data. This is due to RAM being volatile and is best for data that is being used by an application. The volatile part is that it loses the data when the power is turned off. Random Access Memory can be a faster solution to ROM and NVRAM and is also used by data in use and by the Operating System to process data.

ROM

Read Only Memory is used by data at rest typically and is a slower type compared to RAM. ROM is non-volatile and is used by the computer to do a Power on Self-Test which boots the computer up and tests its functionality before the computer turns on. Because it retains information when the power is off ROM is used to store boot code as well as the firmware.

NVRAM

Non-volatile Random Access Memory is used to track configuration updates for things like routers and switches. As it is non-volatile NVRAM it is used by data that needs to persist like configuration files and security keys. NVRAM is somewhat faster than ROM and uses RAM to get updates to things like configuration files on network devices.

Another type of NVRAM that is used by network devices is called Flash. Flash is used by network devices like switches and routers to store IOS images and larger files that can’t be stored on NVRAM. Regular NVRAM in network devices is more for the configuration files. The switches and routers use Flash as more of a hard drive, as it stores IOS images and larger files.

RAM, ROM and NVRAM

These three types of memory are used in different ways to establish better configuration updates like NVRAM, faster processing like RAM and permanent storage like ROM. Random Access Memory is the fastest with NVRAM being the second fastest compared to the slowest which is ROM. The trade-off with ROM is that it is for things that need to persist like firmware.

Knowledge Byte

Complexity of Information is something that is a pain point in studying for certification exams. The best way to overcome this pain point is to be consistent in your studies and break down the information into bite-sized chunks. This will allow you to retain the information when you are ready for the certification exam.

Conclusion

RAM, ROM, and NVRAM are three types of memory that is an important topic in Information Technology. This concept is something that you can look into further and is a computer hardware component that will be helpful to understand if you are going for the CompTIA Tech+ or A+. Understanding the two types of NVRAM is also useful as you go more into your IT career as learning the difference between Flash and NVRAM will help you out with network devices.

Introducing Knowledge Bytes

aarononit.blogspot.com 

This domain is an old domain that is a free domain when it was Blogspot around 2013. I had not posted anything on this website since 2017. Today it was easy to walk in my old shoes, so to speak, as the domain was hooked up to my Blogger account using my Google account. The free domain, aarononit.blogspot.com, has not been used as much so I will be redesigning and posting blog posts on the website.

Populating the content of this blog will be something that I get into more every week. There are some things that will help writing this content and will not be from AI Agent or Chatbot. The way that I approach my writing is by getting into a flow state and just write and rewrite a few times, editing along the way.

Focus of the Blog

This blog will be about information technology including pain points that happen with studying for certification exams in general. The blog, aarononit.blogspot.com, will also have knowledge bytes that are some facts about either information technology or facts about pain points in studying for certifications.

Knowledge Byte

This is the first knowledge byte that I will do to have facts about Information Technology or some pain points studying for IT certifications. The knowledge byte today is the fact that studying for certifications can bring with it some anxiety, which is a completely normal thing unless it is excessive or is about worrying too much. The way to defeat anxiety is to take a daily multivitamin, eat healthier and exercise. You can develop good habits to develop some resistance to anxiety.

Aaron W. DeJong

My sole proprietorship, Aaron W. DeJong, is doing this website, where I will be posting regularly on Tuesday’s at 2:05pm MST for this domain. The mission of Aaron W. DeJong is to help alleviate pain points with studying for certification exams, in particular Computer Networking and Cybersecurity exams. We do this through blogs and articles along with free study plans and other content marketing related to the mission.

If you are interested in the schedule that I have for writing blog posts I have aaronwdejong.net on Friday’s, aaron597.com on Saturday’s, mrcertification.tech will be on Monday’s and aarononit.blogspot.com is on Tuesday’s starting with this blog post. I am working on my business plan, and it will need some more attention before I post it on LinkedIn.

Conclusion

The first blog that I did was on this domain, aarononit.blogspot.com. I wasn’t doing it consistently and didn’t have good content as it was more about the news in 2017. I was not sure how to write a blog back then. This domain will be something that I do in my sole proprietorship, Aaron W. DeJong as a hobby website or a side project for me to work on.

This website is something that is not costing me any money and will enable my messaging to come out in another channel. My sole proprietorship is something that I can scale with the four blogs and continue to work on articles which will be in a longer format than the blog posts.

Welcome Back

This post is the first blog post that I have made on this domain since 2017. I am doing this to extend my sole proprietorship's reach and to connect with the past items that I have talked about on this blog. There is some content that I will be putting on this website to use a free domain that I have used last in 2017. Welcome back guys and I hope that I can help guide you in your journey towards mastery in Information Technology concepts.