Both CNAME and ALIAS records share a common purpose: They map one or multiple domain names (such as those for different departments or regions) to a main target domain. However, their specific uses and functionality differ in various network scenarios. Network administrators need to understand these distinctions to leverage each record type effectively for robust network services. This blog will help you understand the differences between CNAME and ALIAS records and their applications.
What are CNAME records?
A Canonical Name (CNAME) record maps one domain name to another, allowing alias domains or subdomains (like blog.example.com) to be mapped to a primary domain (such as www.example.com). A CNAME record for an alias domain can map to another CNAME record or to a domain name with an A or AAAA record. However, CNAME records cannot point directly to an IP address; they can only redirect to another domain name. This limitation results in multiple DNS resolution steps, which can slightly increase resolution time.
What are ALIAS records?
An ALIAS record enables alias domains or subdomains (like blog.example.com) to point to a root or apex domain (example.com), which is not possible with CNAME records. Unlike CNAME, multiple ALIAS records can point to a single domain, providing a significant advantage during failover scenarios. ALIAS records also have the advantage of automatically resolving the target domain into an IP address without requiring a DNS resolver, leading to quicker resolution times compared to CNAME.
Why can’t you use a CNAME record for a root or apex domain?
Implementing a CNAME record for a root or apex domain would result in conflict with State of Authority (SOA) and Name Server (NS) records. These records contain information about the DNS zone and the authoritative name server for the root domain, but when a CNAME record is created for that domain, the DNS server would give priority to that over SOA and NS records, and CNAME would redirect all the queries for that. And, CNAME wont resolve for the root domain, it would just point from one alias domain or subdomain to another domain. These result in DNS resolution issues and poor network services. Moreover, many DNS providers, including CloudDNS, do not allow CNAME records for root domains.
Why can’t you use an ALIAS record for mapping to a different domain?
In CloudDNS, ALIAS records are restricted by a condition that requires the alias domain’s zone to match the ending of the main domain (for example, if the alias is blog.example.com, the zone must end with example.com). This means that you can’t use an ALIAS record to point to an entirely different domain. If there’s a change in the alias domain name (for instance, from www.example.com to www.exmpl.com), the zone ending would differ, making it incompatible with an ALIAS record. In these cases, a CNAME record is a more effective choice.
Utilize CNAME and ALIAS records efficiently to streamline network service with the help of CloudDNS
With support for multiple DNS record types, including CNAME and ALIAS, ManageEngine CloudDNS allows for flexible and efficient DNS management. By understanding the unique characteristics of these records, you can seamlessly implement the appropriate one in CloudDNS for reliable and optimized DNS resolution.
Try CloudDNS for free now to explore more on the DNS records!
