Summary of Level 3 networks (suggestions for students on Level 3 networks)

A third-level network is a nightmare for many non-computer students and even computer students. I believe there are many people who participate in various training courses in order to take the test and get the certificates of Level 3 networks. Even after the examination, I got a level 3 certificate, but the rest is almost blank, that is, after passing the examination, there is nothing left in my mind.

A few days ago, I also took the Level 3 network examination. I learned step by step according to the review sequence we agreed. Although I do not guarantee that I will pass the Internet, I have learned some knowledge after passing this test. I spent at least half an hour reading a book every day starting two months before the test. I want to read the book many times, I don't need to see the details for the first time (too detailed will make it hard for me to die-I think ). It seems like you do not understand, leave some doubts, it feels good. When reading books for the second or third time, think about the problems left behind in the previous reading. To solve this problem, read and summarize the important questions. Summary is a very necessary process. In the summary process, you can subscribe to your knowledge, or find some knowledge that you think you will but you are not mastered.

The last stage is the question. First, let's talk about your questions. What should I do after you finish? Are you looking at the answer directly, or are you going to find the corresponding knowledge in the book and continue learning from the answer? Of course, the second method is better. I only understand the knowledge, but do not do the question, it is tantamount to talking on paper. When you are doing questions, especially the first two sets of questions, each question goes to the book to find the corresponding knowledge point, which can speed up your learning and consolidate your knowledge, you can also understand the rule of the question in the knowledge point.

When you review a third-level network, you can keep your certificate at any time and use it at any time. The method is simple. Every student has their own method, so my method is not necessarily suitable for everyone.

In the third grade, I feel that the second and third major questions are relatively fixed in form, and the knowledge points are relatively concentrated. At the same time, it is also a third-level Medium score and a relatively high score.

The first question of the second question is not difficult for students who have studied computer science. It is mainly for IP addresses. An IP address is composed of 4 bytes of a 32-digit string. It is usually expressed in dotted decimal notation during the exam.

An IP address consists of a network address and a host address. There are five types of IP addresses, for example:

After learning about the IP address, see what is the subnet mask. Because IP addresses can be divided into network addresses and host addresses, the network address is equivalent to the province and city in your address, and the host address is equivalent to the building and house number in the residential area. If you want to find your home, can you not find it nationwide? It's too slow, so you need to find your minimum range. Within this minimum range, you are looking for your home. This is the role of the subnet mask. It sets all network addresses to 1 and the host address to 0. do you understand this?

Once you know the subnet mask, you will know where it starts, where it is your province and city, where it is a residential area, that is, the demarcation points of the network address and host address. If you want to find your province and city, you can set the host number of the IP address to 0, and the result is the network address (that is, the IP address and subnet mask ). If you are looking for your home in the residential area, if the province and city are useless, you can set it to 0, and the result is the master machine number (in the IP address, the network number is set to 0 ).

In addition, the direct broadcast address in the subnet, the direct broadcast address is the network number of the IP address, and the host number is 1. The first available IP address in the subnet is the network address + 1, and the last available IP address is the broadcast address-1.

All of the above are my understandings. If any errors exist, please point them out! (To be continued ......)

Summary of Level 3 networks (suggestions for students on Level 3 networks)