How to quickly determine whether a DNS resolution error occurs?

in the daily network use and website operation and maintenance process, DNS resolution errors are one of the common reasons that lead to website inaccessibility and abnormal page loading. When many users encounter network problems, they often mistakenly think it is internet bandwidth or server failure, but ignore the DNS process. This article will share a variety of methods for quickly locating DNS problems from a practical perspective to help users of different technical levels to efficiently determine whether DNS resolution errors occur and solve network access obstacles in a timely manner.

First, use the system command to determine the DNS resolution result

The network command that comes with the

system is the most direct tool to judge the DNS resolution status, without the need to install additional software, which is suitable for all users to quickly start troubleshooting.

1, Windows systems use the nslookup command

press the Win + R key combination to open the run window, enter cmd to enter the command prompt, and then enter nslookup + target domain name to get the Internet Protocol Address corresponding to the domain name. If the prompt such as "server failed" and "domain name could not be found" is returned, or the returned Internet Protocol Address is obviously abnormal, it means that there may be an error in DNS resolution. In addition, you can also specify the public DNS server address to query, compare the resolution results of different servers, and further determine whether it is a local DNS or a global DNS problem.

2, Linux/Mac systems use the dig command

open end point and enter dig + target domain name, the command will return detailed DNS resolution records, including domain name server information, resolution time, corresponding Internet Protocol Address, etc. If the returned ANSWER SECTION (response part) is empty, or the SERVFAIL (service failure) status code appears, it can be judged that the DNS resolution is faulty. The dig command also supports specifying specific DNS server queries, which can more accurately locate the root cause of the problem by comparing the output results of different servers.

2, compare the authoritative DNS judgment resolution consistency

The authoritative DNS server of the

domain name stores the official resolution record of the domain name, and comparing the resolution result of the local or public DNS with the authoritative DNS is the core method to determine whether the DNS resolution is accurate.

1, query domain name authoritative DNS server

query the NS records of a domain name through the nslookup or dig command to obtain the authoritative DNS server address of the domain name. For example, enter nslookup -type = NS target domain name, and the returned server address is the authoritative resolution source of the domain name. The resolution records stored by these servers are officially recognized as correct results and are the benchmark for judging whether DNS resolution is wrong.

2, compare the analysis results of different servers

use the nslookup or dig command to specify the authoritative DNS server to query the target domain name, and compare the obtained Internet Protocol Address with the resolution results of the local DNS and public DNS. If the results of the three are consistent, it means that the DNS resolution is normal; if the results of the local or public DNS do not match the authoritative DNS, you can judge that there is a cache abnormality or configuration error in the DNS resolution. You need to further clean the DNS cache or adjust the DNS server settings.

three, through the website access status to determine the abnormal DNS

in addition to directly query the analysis record, you can also reverse determine whether the DNS resolution error occurs through the actual access status of the website, which is closer to the actual use scenario of the user.

1, replacement equipment or network environment testing

if a device cannot access a specific website, but other devices can access it normally under the same network, there is a high probability that there is a problem with the local DNS configuration or cache of the device. At this time, you can try to clean the DNS cache of the device, or change the DNS server address and test again. If the website can be accessed normally after changing the network environment, such as switching from home WiFi to mobile phone hotspot, it means that the DNS server of the original network has a resolution error.

2, test site Internet Protocol Address direct access

obtain the correct Internet Protocol Address of the website through the system command, directly enter the Internet Protocol Address in the browser address bar to access the website. If you directly enter the IP to open the website normally, but enter the domain name cannot be accessed, you can clearly determine that the DNS resolution is wrong; if you enter the IP cannot be accessed, it may be a problem with the server or network link, and eliminate the possibility of DNS resolution failure.

4, with the help of online tools to determine the DNS resolution fault

for users with less technical experience, the online DNS detection tool provides visual troubleshooting results, which can more intuitively determine whether there are errors in DNS resolution.

1, use the global DNS query tool

online tools such as DNS Checker, MXToolbox, etc., support to query the resolution results of the target domain name from DNS servers in multiple regions around the world, and automatically compare the resolution consistency of different regions. If DNS servers in multiple regions return abnormal results, it means that there may be a global problem with the DNS configuration of the domain name; if only some regions are abnormal, it may be a local resolution error caused by DNS cache synchronization delay.

2, check the integrity of DNS resolution records

some online tools will also detect whether the A record, AAAA record, MX record and other resolution records of the domain name are complete and the configuration is compliant. If the tool prompts that a certain type of record is missing or misconfigured, it can also directly determine that there is a problem with DNS resolution. Users can modify the DNS configuration of the domain name according to the prompts to repair the resolution failure.

sum up, judging DNS resolution errors can start from system commands, authoritative DNS comparisons, website access tests, and online tool detection. System commands are suitable for rapid preliminary investigation, authoritative DNS comparisons can accurately locate resolution consistency problems, website access tests are close to actual usage scenarios, and online tools provide visual support for novices. By combining these methods, users can efficiently locate the root cause of DNS failures and restore normal network access in time.