The Wildcard Dilemma: Navigating the SEO Impact of A Records in DNS Entries

by | Digital Marketing, Digital Technology

Domain Name System (DNS) is the backbone of the internet, translating human-readable domain names into IP addresses that machines can understand. While DNS configurations are usually straightforward, the use of wildcard A records introduces a wildcard dilemma that can have significant implications, both positive and negative, on a website’s SEO (Search Engine Optimization) performance.

Understanding Wildcard A Records

Wildcard A records are DNS entries that use an asterisk () as a placeholder for any subdomain not explicitly defined. For example, a wildcard entry like ‘’ would match any subdomain, redirecting traffic to the specified IP address.

Positive Aspects

  1. Ease of Maintenance:
    Wildcard A records simplify DNS management by automatically routing traffic to the designated IP address for any subdomain that does not have a specific record. This can be particularly advantageous for large websites with numerous subdomains.
  2. Scalability:
    Websites that regularly create new subdomains can benefit from wildcard A records as they provide an effortless way to handle an expanding domain structure without having to add individual DNS entries for each subdomain.

Negative Impact on SEO

  1. Duplicate Content Issues:
    One of the most significant concerns with wildcard A records is the potential for creating duplicate content issues. Search engines may index multiple versions of a page, leading to dilution of ranking authority and confusion for search algorithms.
  2. Crawl Budget Exhaustion:
    Search engines allocate a crawl budget to each website, determining how frequently the site is crawled for updates. Wildcard A records can lead to excessive crawling of unnecessary pages, potentially wasting the crawl budget on duplicate or low-value content instead of prioritizing important pages.
  3. SEO Dilution:
    Wildcard A records can dilute the SEO value of a website by spreading link equity and authority across a multitude of subdomains. Instead of consolidating authority on a few key pages, the website’s overall SEO performance may suffer due to dispersed signals.
  4. Keyword Cannibalization:
    With wildcard A records, different subdomains might unintentionally compete for the same keywords. This can lead to keyword cannibalization, where multiple pages target identical search terms, confusing search engines and hindering the site’s ranking potential.

Mitigating the SEO Impact

  1. Selective Use of Wildcards:
    Instead of applying wildcard A records globally, consider using them selectively. Implement specific A records for critical subdomains and reserve wildcard entries for non-essential or dynamic subdomains.
  2. Robust Canonicalization:
    Employ robust canonicalization practices to guide search engines on the preferred version of a page. This can help mitigate the impact of duplicate content issues arising from wildcard A records.
  3. Regular Monitoring and Cleanup:
    Regularly monitor the website’s performance in search results and identify any subdomains causing issues. Implement cleanup measures, such as removing unnecessary wildcard entries and setting up proper redirects for outdated or irrelevant subdomains.


While wildcard A records offer convenience and scalability in DNS management, their impact on SEO cannot be ignored. Website administrators must strike a balance between the ease of maintenance and the potential pitfalls associated with wildcard entries, employing best practices to safeguard their website’s search engine visibility and ranking authority. By implementing selective wildcard usage and diligent monitoring, webmasters can navigate the wildcard dilemma and maintain a healthy SEO profile for their online assets.

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