What is a DNS server? Explanation of core concepts and working principles

in daily network access, we only need to enter a simple and easy-to-remember domain name to open the target website, without memorizing the complex Internet Protocol Address, which cannot be separated from the silent support of the DNS server. Many users only understand the DNS server at the setting level, but do not know its core functions, operating logic and impact on network experience. This article will comprehensively dismantle the relevant knowledge of DNS servers from the perspectives of basic concepts, working principles, type division and common problems, so that you can have a clearer understanding of the underlying logic of network access.

Core definition and function of DNS server?

to understand the DNS server, we must first clarify its position in the network system, it is a key bridge to connect the domain name and Internet Protocol Address.

1 Core Definitions

DNS server is a network server specially responsible for domain name system resolution. Its core function is to convert the user-entered easy-to-remember domain name into an Internet Protocol Address that can be recognized by network devices, which is equivalent to the "address book" in the online world. Without the existence of DNS servers, users can only access network resources through lengthy digital Internet Protocol Addresses, which will undoubtedly greatly increase the threshold for network use.

2, core functions

In addition to the basic domain name resolution function, the DNS server also has extended functions such as cache storage, load balancing, and failover. Cache storage means that the DNS server will temporarily save the corresponding relationship between the recently resolved domain name and the Internet Protocol Address. When the user visits the same domain name again, the cached data can be directly called, and there is no need to repeatedly initiate resolution requests, thereby improving the access speed; load balancing is to assign user requests to different server nodes to avoid overload of a single node and ensure the stable operation of the website.

The complete working principle of the DNS server?

DNS server's domain name resolution process seems simple, but it is actually a complex process of multi-node cooperation, involving multiple levels of server interaction.

1, local resolution request initiation

when the user enters the domain name in the browser and initiates an access request, first check the DNS cache of the local host, if there is a corresponding Internet Protocol Address in the cache, directly return the result to complete the access; if there is no relevant record in the local cache, It will initiate a resolution request to the local DNS server configured in the network.

2, hierarchical analysis process

after the local DNS server receives the request, if there is no corresponding record in its own cache, it will first initiate a request to the root DNS server, and the root DNS server will return the address corresponding to the top-level domain server; then the local DNS server requests the top-level domain server to obtain the address of the authoritative DNS server; Finally, the local DNS server initiates a request to the authoritative DNS server to obtain the Internet Protocol Address corresponding to the target domain name, and then returns the result to the user host, and stores the resolution result in its own cache.

What are the main categories of DNS servers?

depending on the function positioning and deployment scenarios, DNS servers can be divided into several different types, each type has its own unique role.

1, root DNS server

root DNS server is the highest level of the domain name resolution system. There are only 13 groups of root DNS servers worldwide, which are responsible for managing the relevant information of all top-level domains. The root DNS server does not directly store the Internet Protocol Address of a specific domain name, but points to the server address of the corresponding top-level domain. It is the starting and guiding node of the entire resolution process.

2, local DNS server

local DNS server is a server directly associated with the user's network configuration, usually deployed internally by operators or enterprises. It is the intermediate node between the user and the upper DNS server, which handles most of the user's resolution requests, and reduces the load of the upper server through the caching mechanism to improve the resolution efficiency. The DNS server address that many users set daily is actually the address of the local DNS server.

common problems and troubleshooting of DNS server?

in daily network use, DNS server problems will directly lead to the domain name can not be resolved, leading to failure to access the website, it is necessary to master the troubleshooting methods of common problems.

1, common fault performance

DNS servers mainly include resolution timeout, resolution errors, cache pollution, etc. Resolution timeout is usually due to the untimely response of the DNS server, which is manifested as the website loading for a long time without response; resolution error is the return of the wrong Internet Protocol Address, resulting in the open website is not the target website; cache pollution refers to the DNS server's cache is stored in the wrong domain name and IP correspondence, which will continue to mislead users' resolution requests.

2, basic investigation methods

encounter DNS server related problems, first of all, you can test whether the domain name can be resolved to Internet Protocol Address normally through the ping command. If it cannot be resolved, you can try to replace the public DNS server address, such as domestic 114.114.114.114 or foreign 8.8.8.8; at the same time, you can clean up the local DNS cache to avoid the resolution failure caused by cache data errors. The Windows system can complete the cache cleaning through the ipconfig/flushdns command.

sum up, DNS server is an indispensable core component in the network access system. It reduces the threshold of network use through domain name resolution function, and improves the efficiency and stability of network access by caching, load balancing and other functions. From core definition, working principle to type division and troubleshooting, a comprehensive understanding of DNS server related knowledge can help us better deal with daily network problems and optimize network use experience.