Shulou(Shulou.com)06/03 Report--

The purpose of this article is to share with you what the A record in Leader refers to. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

The difference between developing Leader and frontline development is that ordinary frontline developers are often only exposed to business code and do not need to pay attention to anything other than development. But as a development Leader, you need to understand not only the development level, but also the operation and maintenance level.

Recently, the product classmate came to me: boss, the operation has given a demand, and you need to take care of it. Here's the thing: the company needs to access a third-party mail provider, and one of them needs to parse the NS records of the sub-domain name. At that time, I looked confused. What is the NS record of a subdomain name? What are you going to do? Although I can leave the matter directly to the operation and maintenance staff, but as a developer LD with a great sense of responsibility, I have to figure out the whole process.

After some understanding, I learned that there are several types of domain name resolution, including: a record, CName record, MX record, NS record and so on. As a developer, although you do not need to have in-depth knowledge of operations and maintenance, you still need to understand the principles of these different types of parsing. To put it simply, the resolution type of a domain name is the mapping relationship in different usage scenarios.

A record

A record, to put it simply, is to configure a mapping from a domain name to IP. We all know that when we enter a domain name, the browser will help us resolve the IP address corresponding to the domain name on the DNS server, and the browser will eventually access an IP address. The A record here actually configures the mapping of the domain name to IP, so that the DNS server can find the corresponding IP when parsing.

Generally speaking, to set the A record, you only need to go to the management background of the service provider to which your domain name belongs.

In the settings page above, I selected the A record type. The host record is hello.csyimg.com, the record value is 192.168.1.1, and the TTL value is 10 minutes. Then it means that I want to create a mapping for the domain name hello.csyimg.com to the IP of 192.168.1.1, whose cache validity time is 10 minutes.

Then when the user accesses the domain name hello.csyimg.com in the browser, the DNS server forwards the request to the 192.168.1.1 IP. The TTL value here indicates the time it has been cached on the DNS server. When the time is up, it will erase the record, and next time it will go to its corresponding DNS server to get the latest record value.

The significance of the TTL value is that users go through many DNS servers from the browser to the server, while the DNS server receives a large number of requests, and caches are set to improve parsing efficiency. When you visit hello.csyimg.com for the first time, if the local DNS server does not have the A record of hello.csyimg.com, it will be saved this time, and the record will be returned directly on the next visit, so you don't have to travel so far to query. But when we want to change the resolution address, it will take 10 minutes to take effect.

The above is what the A record in Leader refers to. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.