What is a domain name and the Domain Name System (DNS)?
When you are preparing to create a website on the internet, the first step is to register a domain name. A domain name can be thought of as the website’s address on the internet; it consists of a series of characters separated by dots, such as “example.com”. Essentially, it is a label that is easy for humans to remember, used to replace the complex and difficult-to-remember internet protocol (IP) addresses, like “192.0.2.1”. Users can access the corresponding website server by entering the domain name in their browser.
Behind domain names is the operation of a global Domain Name System (DNS). The DNS is a distributed database that is responsible for converting human-readable domain names into machine-readable IP addresses, a process known as “domain name resolution.” You can think of the DNS as the “phonebook” of the internet: when you want to access a website, the system helps you find the correct location of the website’s server.
A complete domain name consists of multiple levels of labels, read from right to left. On the far right is the top-level domain name, such as “.com”, “.net”, “.cn”, etc. Immediately to its left is the second-level domain name, which is usually a unique name that you register. Further to the left, you can add a third-level domain name (commonly known as a “subdomain”), such as “www”, “mail”, or “blog”.
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Domain name registration and DNS record retrieval
To own a domain name, you first need to register it with a domain registrar that is accredited by the Internet Corporation for Assigned Names and Numbers (ICANN). The registration process typically involves checking the availability of the domain name, selecting the registration period, entering the registrant’s information, and completing the payment. Once the registration is successful, you obtain the right to use that domain name for a specified period of time.
After completing the registration process, you will obtain the necessary permissions to manage the domain name’s Domain Name System (DNS) settings. This is typically done through the DNS control panel provided by your registrar. Within this control panel, you will see a list of DNS server addresses, which are referred to as “authoritative DNS servers.” These addresses are usually in the format of “ns1.yourregistrar.com” and “ns2.yourregistrar.com.” These servers serve as the official storage and query points for your domain name’s resolution records; other DNS servers around the world will request resolution information for your domain from these servers.
You need to record the addresses of these authoritative Domain Name System (DNS) servers; they are crucial for directing domain names to the website hosting servers in the next step. Additionally, the registrar’s control panel is where you manage all DNS records, which is the core component for configuring domain name resolution.
Detailed Explanation of Core Domain Name System Record Types
In the Domain Name System (DNS) control panel, you need to configure several core record types in order for the domain name to function properly. Each record has a specific format and purpose.
An A record is the most basic type of record, which directly maps a domain name to an IPv4 address. For example, it can point your primary domain name “example.com” to the IP address of your website server, “192.0.2.1”. The format typically includes the “host record” (e.g., “@” which represents the domain name), the “record type” (A), the “record value” (the IP address), and the “TTL” (Time To Live).
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The AAAA record function is similar to the A record function, but it is used to map domain names to IPv6 addresses in order to accommodate the new generation of internet protocols.
A CNAME (Canonical Name) record, also known as an alias record, allows you to map one domain name to another. For example, you can set “www.example.com” as an alias for “example.com”. This way, when users visit “www.example.com”, the system will look up the A record for “example.com” to obtain the IP address. Using CNAME records makes it easy to manage all the domain name mappings in a centralized manner.
MX records are used to specify the email server addresses that receive emails for a particular domain name. You can set multiple MX records and assign different priorities to ensure the redundancy and reliability of your email service.
TXT records are commonly used to store text information. One of their most common applications is for domain name ownership verification (for use with search engines or cloud service platforms) and for configuring email security policies, such as the Sender Policy Framework (SPF).
Domain name resolution process and troubleshooting
Once you have completed the configuration of the Domain Name System (DNS) records and saved them, the changes will not take effect immediately worldwide. The process of making these changes effective involves a key concept: TTL (Time To Live).
TTL stands for “Time To Live” and is measured in seconds. It determines how long domain name system (DNS) records are retained in cache servers at various levels. For example, if you set the TTL for a domain name to 3600 seconds (1 hour), the recursive DNS servers on the internet will cache that record for 1 hour before querying your authoritative DNS server again to check for any updates. As a result, after you modify a record, it may take up to the duration specified by the old TTL for all global visitors to see the updated record.
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The complete query chain for domain name resolution is as follows: User device -> Local recursive DNS server -> Root DNS server -> Top-level DNS server -> Your authoritative DNS server. The authoritative server finally returns the configured records and caches them along the entire chain.
If you find that domain name resolution is not working or has errors, you can follow these steps to troubleshoot the issue: First, use command-line tools such as “nslookup” or “dig” to check the local resolution results. Next, use online domain name system (DNS) query tools to verify the resolution from different locations around the world, which can help rule out local caching issues. Then, carefully check the record values in the DNS control panel to ensure that they are entered correctly, especially the dots and spaces in the IP addresses. Finally, confirm whether the authoritative DNS server addresses provided by your domain name registrar have been correctly set up with your web hosting provider (if you are using the DNS service offered by the hosting provider).
summarize
Mastering domain name resolution and configuration is a crucial step in successfully converting a domain name into a functional website. The process begins with registering the domain name, and the key lies in understanding and correctly setting the addresses of authoritative Domain Name System (DNS) servers, as well as various DNS records. A records and CNAME records are responsible for directing website traffic, MX records manage email routing, while TXT records are used for verification and security purposes. After making any changes to the records, it is essential to fully comprehend the impact of the TTL (Time To Live) mechanism on the delay in the global propagation of these changes. Through systematic learning and practice, you will be able to manage your domain names with confidence, ensuring that your website and online services operate stably and reliably on the internet.
FAQ Frequently Asked Questions
How long does it take for a domain name registered with ### to start resolving?
After a domain name is successfully registered, the DNS (Domain Name System) configuration can usually be set up immediately. However, it should be noted that the complete synchronization of domain name information across the global DNS network may take several minutes to several hours, depending on the processing speed of the registry and the top-level domain.
Which should be used, a CNAME record or an A record?
If your website hosting service provides a fixed domain name (for example, the domain name of a load balancer on a cloud platform), setting a CNAME record for the main domain name or a subdomain to point to that fixed domain name is the most flexible option, as any changes to the IP address are managed by the service provider. If you have a fixed server IP address, you can directly use an A record to point to that IP address. Typically, the “www” subdomain is set as a CNAME record for the root domain name.
Why is the old website still being displayed when I visit the domain after modifying the DNS records?
This is usually caused by the Domain Name System (DNS) cache. Your local internet service provider or the recursive DNS server on your computer may be holding outdated records. You need to wait for the old records to expire (based on their TTL values) or try to refresh the local DNS cache. Restarting the network services on the server or router can sometimes speed up this process.
How can I know if my domain name resolution has taken effect?
You can use online Global Domain Name System (DNS) query tools to select different query locations and recursive servers to check the resolution results. If the IP addresses returned by multiple independent nodes around the world match the records you have set, it indicates that the resolution has been successfully implemented. Additionally, make sure that the TTL (Time To Live) value set in your DNS records has expired.
Should the domain name system (DNS) server address be the one of the registrar or the hosting provider?
It depends on your choice. The simplest and most straightforward option is to use the Domain Name System (DNS) servers provided by your domain name registrar; all resolution records are managed by the registrar. Many web hosting providers also offer free DNS resolution services, which may optimize resolution speeds or provide convenient one-click resolution templates. You can change the authoritative DNS server address for your domain to the address provided by your hosting provider and then manage the records through the hosting provider’s control panel.
What's next, what's next?
Extended reading and practical knowledge
The following are related to the topic of this article and are suitable for further in-depth reading. Prioritize starting with the article that is closest to your current problem, and gradually expanding to surrounding topics usually works better.
- Starting from scratch: A step-by-step guide on how to efficiently apply for and configure a personal website domain name
- The Five-Step Rule for Mastering Domain Name Security: A Comprehensive Guide to Protection from Registration to Management
- What is a domain name? A comprehensive guide for beginners to experts, from registration to resolution.
- A detailed explanation of the entire domain name resolution process: from entering a website address to the behind-the-scenes journey of loading the web page
- What is a domain name? A comprehensive explanation of its definition, types, and common questions.
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