When managing your domain's DNS resolution, you might encounter a confusing situation: the system displays a "Host record conflict" message, or you might find that your website, email, or other services are intermittently working or pointing to incorrect records. This usually means that there are conflicting or overlapping rules in your domain's DNS settings, causing the DNS system to be unable to determine where to direct visitors. Just like a person receiving two completely opposite instructions simultaneously, the system becomes confused. Understanding the root cause of this conflict and mastering the solution is crucial for maintaining the stability of online services.

When you suspect a host record conflict, a systematic investigation is the first step in resolving the problem. First, log in to your domain's DNS management panel (usually at your domain registrar or a professional DNS service provider) and thoroughly review all resolution records. Pay special attention to duplicate hostnames and whether the same hostname is associated with multiple record types.

Using command-line tools can provide a clearer view. In the terminal or command prompt, you can use the `nslookup` or `dig` commands to query all records for a specific hostname. For example, to view all records for `www.yourdomain.com`, you can use:

dig www.yourdomain.com ANY

This command will return all DNS record types related to that hostname. Carefully examine the output to see if there are any conflicting records.

For more complex conflicts, especially those involving global DNS propagation, online DNS testing tools can be used. These tools can query your domain name resolution results from multiple DNS servers around the world, helping you discover whether different regions are returning inconsistent answers. If some regions return the old IP while others return the new IP, it's likely because the DNS cache hasn't been fully updated, or there's a genuine geographic location-related conflict configuration.

Once the specific type of conflict is identified, targeted measures can be taken to resolve it. For the most common "CNAME conflict with other records," the solution is relatively clear: delete the CNAME record or delete the conflicting record. If you need the hostname to support multiple services simultaneously (e.g., both a website and email), you usually need to abandon the CNAME scheme and use A records directly or other technologies such as URL forwarding.

For conflicts where "multiple A records for the same hostname point to different IPs," the approach needs to be tailored to the specific intent. If these records are used for legitimate load balancing or failover, and all IPs provide the same service, then this is not a true conflict but a normal configuration. However, if these IPs point to different content, the incorrect records need to be deleted, keeping only the correct target IPs. Before deletion, be sure to verify the service status corresponding to each IP to avoid accidentally deleting services that are currently in use.

When conflicts involve more complex scenarios, such as "different DNS servers returning different results," the problem may go beyond simple record conflicts. This could be because your domain name uses multiple DNS service providers (such as your registrar's DNS and your cloud service provider's DNS), and the configurations between these service providers are not synchronized. In this case, you need to identify an authoritative DNS service provider and ensure that all resolution records are managed only by that provider, disabling DNS resolution functions from other service providers.

Conflicts between subdomains and root domains also require special attention. In some cases, you might set an A record for the root domain (`example.com`) while simultaneously setting a CNAME record for the same root domain for CDN services, which violates DNS specifications. Modern DNS service providers usually block this configuration, but older systems may allow it. The typical solution is to use an A record or an ALIAS/ANAME record (a special record that supports CNAME functionality for the root domain) for the root domain, and a CNAME record for subdomains.

When tackling conflicts, a systematic approach can prevent service interruptions. First, document all existing DNS configurations, either by taking screenshots or exporting them as a text file. This provides a rollback reference; if problems arise after modifications, you can revert to a known state.

Adopt a phased modification strategy. Prioritize resolving conflicts affecting core services (such as the main website and corporate email), temporarily reserving records that don't affect critical functions but may cause conflicts, and addressing them after the main issues are resolved. After each modification, wait for DNS propagation (usually a few minutes to a few hours) and use tools to verify that the changes have taken effect.

For complex business environments, consider using version control or history features of your DNS service. Many professional DNS providers offer modification history, allowing you to see who modified which records and when. This is extremely helpful for tracing the root cause of conflicts. If this feature is not available, it is recommended that you manually record the current state before making any modifications.

Prevention is always better than cure. Establishing DNS management practices can significantly reduce the occurrence of conflicts. It is recommended to establish a clear DNS change process, requiring any modifications to go through the steps of recording, review, and implementation. Avoid having multiple people simultaneously have direct modification permissions for the DNS panel. If team collaboration is required, use a DNS service provider that supports team collaboration and professional workflows.

Before adding a new record, get into the habit of checking existing records. Use `dig` or online tools to check what records currently exist for the hostname you intend to modify, ensuring the new record will not conflict with existing configurations.

For critical business domains, consider lowering the TTL value. TTL determines how long a DNS record lives in the cache. Before and after planned DNS changes, temporarily reducing the TTL to a shorter time (e.g., 300 seconds) allows the changes to take effect faster and facilitates quick rollback in case of problems. After the changes stabilize, restore the TTL to a longer time to reduce the pressure on the DNS server.

Regular DNS auditing is also a good habit. Conduct a comprehensive check of all DNS records every quarter or semi-annually, deleting unused records and updating configurations that need modification. Pay special attention to records used for temporary activities, project testing, or decommissioned services, as these are often forgotten sources of conflict.

By systematically identifying, analyzing, and resolving host record conflicts in domain name resolution, you can ensure the reliability and stability of your online services. While DNS configuration may seem highly technical, by following clear steps and best practices, you can effectively manage this critical part of your internet infrastructure and provide users with a seamless access experience.