What does a DNS request mean? The principle and function of DNS requests are explained in detail

in the process of daily use of the Internet, we only need to enter a string of simple domain names to access various websites, but there is actually a complex network protocol process hidden behind it, and DNS request is a crucial part of it. It is the bridge between the domain name entered by the user and the real server address of the website, which determines the efficiency and stability of network access. This article will explain in detail from the basic definition, operation principle, core role of DNS request and other dimensions to help readers thoroughly understand this key technology at the bottom of the Internet.

What is the basic definition of a DNS request?

to understand DNS requests in depth, it is first necessary to clarify its basic concepts and its positioning in the network access process.

1, the core definition of DNS requests

DNS request is a query sent by a user device or local DNS server to a higher-level DNS server to convert an easily memorable domain name into an Internet Protocol Address that a computer can recognize. Because devices in the Internet can only communicate through Internet Protocol Addresses, and it is difficult for ordinary users to remember long strings of numbers, DNS requests assume the role of "translators", allowing the mapping of domain names and Internet Protocol Addresses to be completed automatically.

2, DNS request initiation scenario

DNS request initiation scenarios are very extensive. When the user enters the domain name in the browser to access the website, the device will automatically initiate a DNS request; using APP to access network resources, smart devices to synchronize data and other operations will also trigger DNS requests. Simply put, almost all actions that need to access the network through the domain name cannot be separated from the support of DNS requests.

What is the operating principle of DNS requests?

DNS requests is a complex process of hierarchical queries, involving multiple layers of DNS servers working together to ensure that query results can be returned quickly and accurately.

1, the local cache query phase of DNS requests

When a user initiates a network access request, the device first checks the local DNS cache to see if there is an Internet Protocol Address record corresponding to the domain name. If there is a valid record in the cache, the result will be returned directly without initiating an external DNS request, which can greatly reduce the access response time. The valid period of the local cache is determined by the TTL value set by the DNS server, and the cache record will be automatically invalidated after expiration.

2, hierarchical recursive query phase of DNS request

if there is no corresponding record in the local cache, the device will initiate a DNS request to the local DNS server. The local DNS server first checks its own cache, if there is no result, it will initiate a query to the root DNS server, and the root server returns the top-level domain DNS server address; then the local DNS server queries the top-level domain server to obtain the authoritative DNS server address; finally initiates a DNS request to the authoritative DNS server, obtains the Internet Protocol Address corresponding to the domain name, and then returns the result to the user device, and stores the record in its own cache.

What are the core functions of DNS requests?

DNS request is not just a simple address translation tool, it plays a number of core roles in the Internet system to ensure the efficiency and stability of network access.

1. Implement the mapping between domain names and Internet Protocol Addresses

this is the most basic and core role of DNS requests. Through DNS requests, users do not need to remember complex Internet Protocol Addresses, but only need to enter simple domain names to access target websites. Without DNS requests, users have to manually enter Internet Protocol Addresses every time they visit the network, which will greatly reduce the ease of use of the Internet and hinder the popularization and development of the Internet.

2, optimize network access response speed

DNS request caching mechanism can effectively optimize network access speed. When a DNS request for the same domain name is initiated again, the device or local DNS server can directly obtain the result from the cache without repeating hierarchical queries. At the same time, some intelligent DNS services can also assign the nearest server Internet Protocol Address to the user through intelligent resolution of DNS requests, further shortening the delay of data transmission.

3, to ensure the stability of network access

when a server node fails, DNS requests can be updated through the records of the authoritative DNS server to map the domain name to the Internet Protocol Address of the standby server to achieve seamless switching of services. In addition, the hierarchical query mechanism of DNS requests also has certain fault tolerance. If a DNS server at a certain level is temporarily unavailable, it can also complete the query through other available nodes to ensure that network access will not be easily interrupted.

common problems and troubleshooting methods of DNS requests

although the process of DNS request is relatively mature, it will encounter various problems in actual use, which will affect the network access experience.

1, DNS request timed out troubleshooting

DNS request timed out is one of the common problems, which is that the website cannot be opened for a long time after entering the domain name. When troubleshooting, you can first check whether the network connection of the device is normal. If the network is normal, you can try to change the DNS server address, such as switching to a public DNS server; you can also clear the local DNS cache to avoid invalid records in the cache affecting the normal query of DNS requests.

2, DNS request returns an error result

sometimes DNS requests will return the wrong Internet Protocol Address, causing users to visit the wrong website or unable to access the target resource. This situation may be caused by DNS cache contamination. At this time, it is necessary to completely clear the local and browser DNS cache. At the same time, it is recommended to use DNS servers with anti-pollution functions to ensure that DNS requests can obtain accurate mapping records.

sum up, DNS request is an indispensable key link in the Internet access process. It undertakes the mapping query of domain name and Internet Protocol Address, optimizes network access experience through hierarchical query and caching mechanism, and guarantees the stability of network services. Whether it is ordinary users or network practitioners, understanding the principle and function of DNS request can help us better use the network, troubleshoot network problems, and improve the efficiency and security of network access.