Among problems such as website inaccessibility, abnormal page loading, and inconsistent access speeds, domain name resolution errors are arguably one of the most easily overlooked yet most common root causes. Many novice website owners, when faced with an inaccessible website, often immediately assume server downtime, program errors, or network attacks, rarely checking the domain name resolution itself, resulting in a significant waste of time. In reality, even if the server is running normally and the website program is flawless, users will still be unable to access the website if there is a problem with domain name resolution.

　　Domain name resolution, simply put, is the process of converting easily remembered domain names into IP addresses that computers can recognize. When a user enters a domain name into their browser, the browser doesn't know where the server is; it queries the DNS system level by level to obtain an IP address before establishing a connection. If any step in this process malfunctions, it can lead to various errors such as "server not found," "connection timeout," and "abnormal redirection."

　　Because domain name resolution is the first step in website access, an error in it often affects the entire website, not just a single page. Whether it's a corporate website, an e-commerce platform, or a personal blog, any DNS resolution anomaly will drastically degrade the user experience, and in severe cases, may even lead to business interruption.

　　In actual operation and maintenance, website failures caused by domain name resolution errors typically fall into the following categories:

　　The most common is that the domain name does not resolve correctly to the server IP. This often occurs after a new website goes live or the server is replaced. When the website owner fills in the DNS records in the domain management backend, if the IP address is entered incorrectly by one digit, or if it still points to the old server, users will access a non-existent address. The symptom is usually a browser message saying "Cannot access this website" or "Connection failed." For beginners, this type of problem is very confusing because the server itself is normal, and it can be accessed directly by IP, but it remains inaccessible by domain name.

　　The second common situation is that DNS resolution is not effective or is incompletely effective. Domain name resolution is not effective immediately; it has a caching mechanism, commonly known as TTL. When the website owner has just modified the DNS records, the old resolution results may still be cached in the local network, the ISP's DNS, and even the user's browser. This can lead to some users accessing the website normally, while others cannot. The website owner may test it and find no problems, but users from other regions frequently report being unable to access it. This "intermittent" issue is often caused by a failure to refresh the DNS cache.

　　The third type of problem is incorrect configuration of DNS record types. Common DNS record types include A records, CNAME records, and MX records. A records are used to point to IPv4 addresses, while CNAME records are used for aliases. If an A record is incorrectly configured as a CNAME record, or if a CNAME record is used in a location that does not support CNAME, it can cause resolution failures or access errors. This type of error is particularly prone to occur when binding CDNs, object storage, and load balancers. New users who simply follow tutorials mechanically may easily overlook the limitations.

　　The fourth situation is a conflict between domain name resolution and CDN or cloud services. Many websites connect to CDNs to improve access speed. After connection, domain name resolution usually no longer points directly to the server IP, but to an address assigned by the CDN. If subsequent configurations are duplicated on the cloud server or CDN backend—for example, enabling CDN while simultaneously resolving the domain name back to the origin server's IP—it can lead to access loops, 403 errors, or garbled page content. While it may appear to be a CDN malfunction, the root cause is actually improper domain name resolution configuration.

　　The fifth, more subtle type of error is DNS corruption or hijacking. In certain network environments, when users access a domain, the DNS returns a tampered address instead of the real IP set by the website owner, potentially redirecting them to an advertising page or rendering the site inaccessible. This type of problem often only occurs in specific regions or with specific network providers; the website owner may find it works correctly in their own tests but receive frequent user complaints. Although this isn't entirely due to configuration errors, the result is still a website malfunction caused by abnormal domain name resolution.

　　The sixth common problem is normal domain name resolution, but a port or protocol mismatch. For example, the domain name might point to a server IP, but the server only listens for HTTPS, while the user accesses HTTP after resolution. Alternatively, an incorrectly deployed SSL certificate can also mislead users into believing it's a domain name issue. Strictly speaking, these problems are caused by a mismatch between DNS resolution and service configuration, ultimately leading to website inaccessibility.

　　So, what direct impacts do these domain name resolution errors have on a website?

　　The most direct impact is that the website becomes completely inaccessible. This is fatal for corporate and e-commerce websites; even a few minutes of downtime can result in lost orders, lost customers, and a decline in brand trust. Frequent inaccessibility during search engine crawling can also affect website indexing and ranking.

　　Secondly, there's unstable access. Some users can access the site, while others cannot, or the same user may experience different results at different times. This is very difficult for website owners to troubleshoot and will give users the impression that the website is unprofessional, causing them to abandon the site.

　　Furthermore, there's the risk of incorrect redirection. If the DNS resolution is pointed to the wrong IP or is compromised, users may be redirected to unfamiliar websites or even pages with security risks. This not only affects user experience but can also pose legal and security risks to the website.

　　For beginners, mastering a clear troubleshooting approach is crucial. When you suspect a domain name resolution (DNS) issue, you can start by checking the following:

　　First, access the server directly using its IP address. If the website opens normally via the IP address but not the domain name, the problem is likely with DNS resolution or related configurations. Second, use DNS lookup tools for different regions to check if the returned resolution results are consistent. If the returned IP addresses are inconsistent, focus on whether the DNS records have been recently modified or if there are caching issues. Third, log in to the domain management backend and verify the type, host record, and value of each DNS record to ensure they are completely consistent with the server or CDN provider's requirements.

　　If the above steps do not reveal any obvious errors, you can also check if CDN, proxies, firewalls, or other intermediate services are enabled to prevent the DNS resolution from pointing to the wrong service architecture. Also, pay attention to whether the domain name is about to expire or has been suspended from DNS resolution; these seemingly "basic" issues are very common in actual operations and maintenance.

　　In summary, DNS resolution errors, while seemingly simple, are one of the most frequent types of website malfunctions. It's easily overlooked because the DNS resolution process itself is "invisible" to both users and website owners, yet it undeniably determines whether a website can be accessed. For novice website owners, understanding the basic principles of DNS resolution, developing habits such as keeping records before making changes, patiently waiting for the changes to take effect, and verifying access results from multiple perspectives, can help avoid most website malfunctions caused by DNS resolution errors.