欧博百家乐What Is DNS (Domain Name System)?
More specifically, query resolution in the DNS involves several key processes and components
Query initiation. A user enters a domain name, such as “ibm.com,” into a browser or app. If the IP address for the site in question is not in the browser’s cache, the request is sent to a recursive DNS resolver. Typically, the user’s device has predefined DNS settings, provided by the ISP, that determine which recursive resolver receives the request.
*This process is evolving, as many modern browsers support DNS over HTTPS (DoH), which enables DNS lookup over HTTPS, and many providers have servers set up for this type of look up. For example, if you use Firefox in the United States, it will by default send the query to a Cloudflare DoH server instead of the local ISP provider’s resolver. DoH is becoming more popular because it offers increased privacy and better performance and other benefits.
Recursive resolver. The recursive resolver checks its own cache for the domain’s corresponding IP address. If the recursive resolver does not have the necessary records in its cache, it initiates the lookup process, starting at the root server.
Root name server. The recursive resolver queries a root name server, which responds with a referral to the appropriate TLD server for the domain in question (the TLD name server responsible for “.com” domains, in this instance).
TLD name server. The resolver queries the “.com” TLD name server, which responds with the address of the authoritative name server for “ibm.com.”
Query resolution. The recursive resolver returns the IP address to the user’s device. The browser or app can then initiate a connection to the host server at that IP address and access the requested website or service. The browser and resolver cache records in accordance with their respective configurations and TTLs.