1. 關於CCNA和Cisco系列認證

   1. CCNA認證考試，可以說是無數互聯網從業人員的啟蒙教程，從誕生以來一直扮演著極其重要的角色。CCNA是Cisco認證體系當中最基礎，也是我認為最重要的課程。因為凡事開頭難，它擔負著從0到1的轉變。

   2. 我們先來瞭解一下Cisco認證體系。

      1. Cisco 認證體系最早於 1993 年推出，並且只有CCIE這個最高級別的認證，在1998年推出了CCNA和CCNP。最初，Cisco 的培訓和認證項目，是為了確保 Cisco 自己的員工和合作夥伴具備必要的技能，以支援和實施 Cisco 的網路解決方案。也就是說，在一開始，這個認證體系只是針對內部需求而生。但隨著時間的推移，Cisco設備在整個互聯網市場的份額越來越大，這些認證被擴展到公眾，以應對在更廣泛市場中，對專業網路人員日益增長的需求。

      2. Cisco認證體系，從級別來看由低到高分別是CCNA思科認證網路助理，CCNP思科認證網路專家和CCIE思科認證互聯網專家，三個級別。從誕生至今這幾十年中，不斷的迎合技術發展，和實際需求，這套認證體系經過了多次的反覆運算。現在更側重於通過不同的技術，類別結合這三個級別進行組合式的劃分。比如本套課程CCNA，目前只有Enterprise，企業網路這一個方向，並且Enterprise這個方向，在CCNP和CCIE中均有出現，它們的區別體現在深度和廣度上的不同，不要看CCNA只是初級認證，但它包含的內容最廣，這也是為什麼我說CCNA的難度較高的原因之一。在CCNP以及CCIE中，會針對Enterprise中的某一個方向，在深度上提高要求，比如CCNP Enterprise中有多項考試，300-410是針對實施企業高級路由和服務方向，300-420是針對設計企業網路方向，300-425又是針對設計企業無線網路方向等等。

   3. Cisco不僅僅是一家網路硬體設備製造商，更是整個互聯網技術發展的推動者，Cisco公司中的很多專家，都同時在IEEE或者IETF中任職。參與開發和定制互聯網相關技術標準。這就是為什麼Cisco系列認證具有極高含金量的原因之一。

2. 計算機網路究竟是在學什麼？

   1. 我們學習電腦網路相關技術時，究竟是在學習什麼？這是很多初學者，甚至從業多年的專業人員都說不清的一個問題。我認為，我們學習的是兩個大的方向。

   2. 第一個方向，是各種互聯網相關協議中包含的專業術語、協議解決的問題、工作過程和原理等等，比如什麼IPv4，什麼是OSPF，什麼是STP，這些協議或者技術基本都是由IEEE或者IETF開發制定。這些開放的公共知識，佔據了我們學習中相當大的一部分。

   3. 第二個方向，就是學習設備的作業系統使用方法，也就是在設備上如何具體實現這些技術，比如我們在Cisco的設備上配置介面位址，各類路由切換式通訊協定等等。當我們熟練掌握Cisco設備的使用之後，再去使用其他廠商的設備時，您會發現，基本看一下產品手冊就可以輕鬆駕馭。很多其他的設備只是將一些命令中的關鍵字做了替換，在早期甚至是一摸一樣，系統的操作邏輯基本和Cisco相同。

3. CCNA考察内容

   1. CCNA作為我們進入這個行業的引路人，目前最新的考試編號為200-301。這是一個面前構建企業網路方向的認證，全稱為，實施和管理Cisco解決方案Implementing and Administering Cisco Solutions

   2. 包含網路基礎Network Fundamentals，網路訪問Network Access，ip連接IP Connectivity，IP服務IP Services，安全基礎Security Fundamentals和自動化及可程式設計性Automation and Programmability六個模組。這基本涵蓋了，我們需要瞭解的大部分互聯網相關技術。當我們完成CCNA學習後，可以說我們的相關知識已經有了幾公里的寬度，但是在具體知識點的深度並不夠，這就需要在CCNP或者CCIE中去專項提升。

4. 本套CCNA課程內容

   1. 在我的課程當中，包含您在CCNA學習時，需要掌握的所有知識點，有基礎的OSI及TCP/IP模型，IPv4，IPv6內容，讓您掌握網路的分層構架，以及ip位址的分類及編址規則。

   2. 直觀化的Cisco IOS系統使用方法，在瞭解IOS的結構的同時，掌握命令的輸入和配置規則。

   3. 詳盡的交換和路由內容，包含VLAN，VTP，STP，乙太網通道及各類路由式通訊協定如Static，RIP，EIGRP和OSPF的工作原理及配置方法，還有安全，自動化，無線網路等等內容，再結合這些技術出現的背景和發展歷史，讓您更全面透徹的瞭解這個龐大的網路帝國。

   4. 為了一些知識點的連貫，我還會延申一些在CCNP甚至CCIE中的內容。當我們站的更高時，一定可以更輕鬆的駕馭CCNA考試。

   5. 我的課程中，還會包含大量的課程附件，比如相關技術的RFC文檔，課程中出現的圖表及內容總結，還有實驗環境的拓撲圖等等。

   6. 除此以外還有相關知識點的試題講解，在熟悉CCNA考試題類型的同時，還可以加深我們對知識點的理解。

   7. 我希望將課程打造成一套，以知識點為核心的視頻手冊或者工具，當您在學習或者工作中遇見問題後，可以快速的從我的課程中定位知識點，通過觀看視頻以及課程附件後迅速解決您遇到的問題。所以我會持續對課程進行升級和維護，除了應對未來考試內容的變化以外，還會陸續怎加新的內容，如果您購買了我的課程，那麼後續的這些升級和DLC都是免費的。

5. 如果您正在備考CCNA，或者想學習計算機網絡、安全等方面的相關知識，相信本套課程一定會成爲您不錯的選擇，希望通過我的系列課程，助您在學習和工作上一臂之力！

About CCNA and Cisco Certifications

The CCNA certification exam can be considered the introductory tutorial for countless internet professionals. Since its inception, it has played an extremely important role. CCNA is the most basic and, in my opinion, the most important course in the Cisco certification system. Starting is always the hardest part, and it bears the responsibility of transforming from 0 to 1.

Let's first understand the Cisco certification system.

The Cisco certification system was first introduced in 1993, and initially, it only had the highest level of certification, CCIE. In 1998, CCNA and CCNP were introduced. Initially, Cisco's training and certification programs were designed to ensure that Cisco's own employees and partners had the necessary skills to support and implement Cisco's network solutions. In other words, at the beginning, this certification system was created to meet internal needs. However, over time, as Cisco devices gained an increasing share of the entire internet market, these certifications were extended to the public to address the growing demand for professional network personnel in the broader market.

The Cisco certification system, from the level perspective, is divided into three levels from low to high: CCNA (Cisco Certified Network Associate), CCNP (Cisco Certified Network Professional), and CCIE (Cisco Certified Internetwork Expert). Over the past few decades since its inception, this certification system has continuously adapted to technological developments and actual needs, undergoing multiple iterations. Currently, the focus is more on combining different technologies and categories within these three levels. For example, the current CCNA course only has one direction: Enterprise Networks. This Enterprise direction also appears in CCNP and CCIE, with differences in depth and breadth. Although CCNA is only an entry-level certification, it covers the widest range of content, which is one reason why I say CCNA is quite challenging. In CCNP and CCIE, the focus is on increasing the depth of specific directions within Enterprise. For example, in CCNP Enterprise, there are multiple exams, such as 300-410 for implementing enterprise advanced routing and services, 300-420 for designing enterprise networks, and 300-425 for designing enterprise wireless networks, among others.

Cisco is not just a network hardware manufacturer but also a promoter of the entire internet technology development. Many experts in Cisco also hold positions in IEEE or IETF, participating in the development and formulation of internet-related technical standards. This is one of the reasons why Cisco certifications are highly valuable.

What Are We Learning in Computer Networks?

When we study computer network-related technologies, what exactly are we learning? This is a question that many beginners and even experienced professionals find hard to answer. I believe we are learning in two major directions.

The first direction is the professional terms, problems solved by protocols, working processes, and principles contained in various internet-related protocols, such as IPv4, OSPF, and STP. These protocols or technologies are mostly developed and formulated by IEEE or IETF. This open public knowledge occupies a significant part of our learning.

The second direction is learning how to use the operating systems of devices, specifically how to implement these technologies on devices. For example, configuring interface addresses and various routing and switching protocols on Cisco devices. Once we master the use of Cisco devices, we will find that using other manufacturers' devices is relatively easy, often just requiring a look at the product manual. Many other devices only replace some keywords in commands, and in the early days, they were even identical, with the system's operating logic basically the same as Cisco's.

What Does CCNA Teach?

As the guide for our entry into this industry, the latest CCNA exam code is 200-301. This certification is oriented towards building enterprise networks, fully named "Implementing and Administering Cisco Solutions."

It includes six modules: Network Fundamentals, Network Access, IP Connectivity, IP Services, Security Fundamentals, and Automation and Programmability.

These modules essentially cover most internet-related technologies we need to understand. After completing CCNA, we can say our relevant knowledge has a few kilometers of width, but the depth of specific knowledge points is not enough, which needs to be enhanced in CCNP or CCIE.

Content of My CCNA Course

In my course, all the knowledge points you need to master during CCNA learning are included. It covers the basics of the OSI and TCP/IP models, IPv4, and IPv6, allowing you to understand the layered architecture of the network and the classification and addressing rules of IP addresses.

It also includes a visualized method of using the Cisco IOS system, mastering the input and configuration rules of commands while understanding the structure of IOS.

Detailed switching and routing content, including VLAN, VTP, STP, Ethernet channels, and various routing protocols such as Static, RIP, EIGRP, and OSPF, along with their working principles and configuration methods, as well as security, automation, wireless network, and other content. Combined with the background and development history of these technologies, you will have a more comprehensive and thorough understanding of this vast network empire.

To maintain the continuity of some knowledge points, I will also extend to some content in CCNP and even CCIE. When we stand higher, we can certainly better handle the CCNA exam.

My course also includes a large number of course attachments, such as RFC documents related to technologies, charts, and content summaries appearing in the course, and topology diagrams of the experimental environment.

Additionally, there are explanations of related knowledge point test questions, familiarizing you with the types of CCNA exam questions while deepening your understanding of the knowledge points.

I hope to create a course that serves as a video manual or tool centered on knowledge points. When you encounter problems during study or work, you can quickly locate the knowledge points from my course and solve your problems quickly by watching the videos and course attachments. Therefore, I will continuously upgrade and maintain the course, not only to cope with future changes in exam content but also to add new content gradually. If you purchase my course, these subsequent upgrades and DLCs are free.

If you are preparing for the CCNA or want to learn about computer networks, security, and other related knowledge, I believe this course will be a good choice for you. I hope my series of courses can help you in your study and work!