in the process of website operation, domain name resolution failure is a problem often encountered by many webmasters and operation and maintenance personnel. It may lead to website inaccessibility, email service interruption, and directly affect user experience and business development. Many people are at a loss when encountering such problems. In fact, as long as they master scientific troubleshooting logic and processing methods, they can quickly solve the problem. This article will share the troubleshooting ideas and coping strategies of domain name resolution faults in an all-round way, and help you resolve the crisis efficiently.
How to preliminarily judge the fault of domain name resolution?
encounter problems such as website inaccessibility, first confirm whether it is a domain name resolution failure to avoid misjudgment and waste of troubleshooting time.
1 Use local parsing tools to detect
in the command line of the computer or server, query the Internet Protocol Address corresponding to the domain name through tools such as ping, nslookup or dig. If the returned Internet Protocol Address does not match expectations, or shows that the domain name cannot be resolved, there is a high probability that there is a problem with the domain name resolution. For example, after pinging the domain name, it shows request timed out, nslookup prompts non-authoritative reply or no record, which points to the domain name resolution exception.
2, compare multiple end point analysis results
replace the end point of different network environments for testing, such as accessing websites with mobile phone traffic, or asking friends in different places to help detect. If only a single end point cannot be resolved normally, it may be a local DNS cache or network problem; if multiple end points and multiple networks have abnormal resolution, it can be basically determined that it is a fault at the domain name resolution level.
What are the common causes of domain name resolution failure?
the positioning fault belongs to the domain name resolution problem, it is necessary to further investigate the specific incentives, and different incentives correspond to different processing directions.
1, domain name status is abnormal or expired
domain name is locked, redeemed or expired, it will directly lead to the failure of domain name resolution. You can check the status of the domain name through the background of the domain name registrar. If the lock status such as clientHold and serverHold is displayed, you need to contact the registrar to unlock it. If the domain name has expired, you need to complete the renewal in time and wait for the status to be restored. Generally, the domain name resolution will gradually return to normal within 1-24 hours after the renewal.
2, DNS server configuration error
domain name resolution depends on the configuration information of the DNS server, common errors include the wrong type of parsing record, such as writing the A record as a CNAME record; the wrong record value is filled in, such as the Internet Protocol Address input is wrong; or the TTL setting is unreasonable, resulting in the delay of parsing updates. In addition, if the DNS server itself is down or network failure, it will also affect the normal effect of domain name resolution.
3, domain name resolution cache is not updated
the local DNS server or end point device will cache the domain name resolution result. If the resolution record has just been modified, the old resolution information will still be used when the cache has not expired, resulting in a seemingly domain name resolution failure. In this case, even if the domain name resolution record is already in effect in the background of the service provider, the end point cannot obtain the new resolution result.
3. Specific repair plan for domain name resolution failure?
clear the cause of the domain name resolution failure, you can take targeted repair measures to quickly restore the normal resolution function of the domain name.
1 Repair domain status and DNS configuration
If the domain name expires or is locked, immediately complete the renewal or submit the unlocking application in the registrar background, and wait for the domain name status to return to normal, check whether the domain name resolution record is complete. If the DNS configuration is wrong, log in to the domain name resolution service provider background, check the type of resolution record, record value, TTL and other information, and save it after correcting the error. Generally, the new resolution record will take effect gradually within the time set by TTL.
2, refresh the domain name resolution cache
For local endpoint caches, you can refresh the cache by executing ipconfig /flushdns (Windows systems) or sudo dscacheutil -flushcache (Mac systems) from the command line. For local DNS server caches, you can restart the DNS service if you have permission, or wait for the cache to expire naturally; you can also replace public DNS servers, such as using 114.114.114.114 or 8.8.8.8, to quickly get new domain name resolution results.
3, contact the service provider to troubleshoot the server failure
if it is suspected that the DNS server itself is faulty, contact the technical support of the domain name resolution service provider in time, provide domain name information and test results, and let the service provider check the server status and network connectivity. If the service provider's DNS node fails, it will generally be repaired in a short time, or it can be temporarily switched to an alternate DNS server to ensure the normal operation of domain name resolution.
4. How to prevent domain name resolution failure from happening again?
solve the current domain name resolution failure, it is also necessary to do a good job of long-term protection to avoid similar problems recurring and ensure the stability of website services.
1, regularly check the domain name and resolution status
set the domain name expiration reminder, bind the mailbox and mobile phone number in the registrar background, and receive the renewal notice 1-2 months in advance to avoid domain name resolution failure due to domain name expiration. At the same time, log in to the domain name resolution background every week or month to check the validity of the resolution records, confirm that the DNS server node is running normally, and clean up the useless resolution records in time.
2, configure multi-node DNS server
configure at least 2 DNS servers of different operators for the domain name. When the main server fails, the backup server can continue to provide domain name resolution services to reduce the risk of single point failure. At the same time, choose domain name resolution service providers with good reputation and high stability, and give priority to service providers that support intelligent resolution, downtime switching and other functions to improve the reliability of domain name resolution.
To sum up, the troubleshooting and processing of domain name resolution faults needs to follow the logic from initial judgment to positioning, and then to repair and protection. Quickly confirm the fault type through local tools and multi-end point detection, locate incentives from domain name status, DNS configuration, cache, etc., and then take targeted repair measures. Finally, do regular inspections and multi-node configuration for long-term protection. Mastering this method can efficiently solve domain name resolution faults and ensure the stable operation of the website.