CNAME vs A Record: Which DNS Record Should You Use?
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Key Takeaways
- The Domain Name System (DNS) functions like a phonebook, translating domain names into IP addresses for website access.
- CNAME records link subdomains to a parent domain, allowing for flexible management of website addresses.
- A records are essential for connecting domain names directly to their corresponding IP addresses.
- CNAME records help maintain accessibility by reducing the need to change multiple A records when a site’s IP address changes.
- Understanding the differences and applications of CNAME and A records is crucial for effective domain management.
The Domain Name System (DNS) stores records that contain instructions that direct Internet traffic to your domain address. The system functions as a navigation system that shows users the correct server location after they enter their domain address into their web browser.
The two primary DNS record types include A records and CNAME records. Your website needs proper accessibility, reliability, and easy management, which requires you to understand the differences between these two.
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What is a CNAME Record?
A DNS CNAME record provides an association for alias domains and subdomains to the main parent domain. Here C stands for ‘canonical.’ This refers to the connection of subdomains to the canonical name domain or the records delivered for another DNS hostname.
A CNAME record enables subdomain redirection to another domain name, which typically points to the parent domain. The subdomain will point to the same server as the target domain through this mapping process. The web server configuration determines which webpage users will access; the CNAME record does not affect this process.
CNAME records are helpful when the webmaster alters the IP address of the website. So, instead of changing A records for all the subdomains, you only have to change the A record for the parent website.
You can check your CNAME records using a CNAME record lookup tool.
What is an A Record?
The purpose of DNS A record is to help you land the desired website without entering the IP address. It contains records of IP addresses corresponding to particular websites; thus, A stands for ‘address.’ Without an A record, you won’t be able to reach a website through its domain name.
Whenever you type any domain name into your browser’s address bar, the responsible server returns the IP address for the domain, which is located in the zone files. This lets you navigate a website.
For instance, you can enter the domain name ‘powerdmarc’ into your browser’s address bar, and the DNS A record digs out the IP address.
Note that A records only work with IPv4 addresses and not IPv6. You would require an AAAA record for IPv6.
You can check your A records using an A record lookup tool.
Key Difference Between a DNS A Record and CNAME Record
Your domain management requires knowledge of A records and CNAME records because they serve different purposes. The two record types direct website traffic through different methods, which affect system performance and operational flexibility.
| Hostname/ Domain/ Subdomain | DNS Record Type | Destination |
| example.com | A record | 12.345.67.89 |
| www.example.com | CNAME record | example.com |
| blog.example.com | CNAME record | example.com |
| shop.example.com | CNAME record | shop.work.com |
Core functions
An A (Address) record enables domain name resolution to specific IP addresses. The Internet uses this method to find servers through direct IP address connections.
Example:
website.com → 192.0.2.1
The browser uses A records to find the server address when users enter example.com into their address bar.
A CNAME (Canonical Name) record enables domain name redirection to another domain name instead of using IP addresses. The system functions as a substitute name for other domains.
Example:
blog.website.com → website.com
The system redirects visitors who access blog.website.com to example.com which then performs IP address resolution.
Comparison: While A records provide a direct route to a server, CNAME records add an extra step but make domain management easier by pointing multiple names to a single canonical domain.
Use cases
In practice, choosing between A and CNAME records depends on what you’re trying to achieve.
| Record Type | Common Use Cases | Notes |
| A Record | Primary domains, pointing directly to hosting IPs | Best for root domains like example.com |
| CNAME | Subdomains, redirecting multiple names to one domain | Simplifies updates when IP addresses change |
In short, A records are typically used for root domains or services requiring direct IP mapping, such as web servers or mail servers.
CNAME records are ideal for subdomains or services where multiple domain names should resolve to the same target. They simplify management because any change to the canonical domain automatically applies to all CNAME aliases.
Performance and flexibility
Another distinction between A records and CNAME records emerges from their impact on system performance and operational flexibility.
The IP address lookup process of A records leads to direct IP address resolution, which produces fast response times and single DNS lookup operations.
The DNS lookup process for CNAME records involves two steps because it first finds the alias domain’s canonical domain before performing an IP address resolution. The additional DNS lookup process introduces a minimal delay, which remains unnoticeable to most users, although it creates a technical performance difference.
The system allows users to manage their domains through CNAME records because these records enable simple IP address updates and multiple subdomain redirections to a single resource. A records provide immediate IP address resolution, but users must update each record separately when IP addresses change.
Coexistence rules and limitations
DNS configuration standards establish particular rules that determine how A and CNAME records should interact with each other.
A records do not face any restrictions when they exist with other record types. CNAME records need to direct users to a canonical domain name. They cannot have any other records sharing the same name.
Using a CNAME at the root domain level breaks DNS standards, which might cause problems with email delivery and web hosting services. Root domains should use A records or DNS provider-specific alias solutions instead of CNAME records for safety reasons.
Which One Should You Use?
Choosing between a CNAME and an A record depends on your specific domain setup and management needs.
Use an A Record when:
- You need to point a root domain (e.g., example.com) directly to an IP address.
- You want the fastest possible DNS resolution without additional lookups.
- Your server IPs are stable and rarely change.
Use a CNAME Record when:
- You want to point a subdomain (e.g., blog.example.com) to another domain rather than an IP.
- You need easier management for multiple aliases pointing to the same canonical domain.
- Your target IPs may change frequently, and you want updates to propagate automatically.
If speed and direct mapping are critical, choose A records; if flexibility and simplified management are the priority, CNAMEs are the better option.
Conclusion
Understanding the difference between CNAME and A Records is essential for effective DNS management. The main difference lies in how they map domain names: A records link directly to an IP address, while CNAMEs point to another domain.
By selecting the appropriate record type, you can enhance usability, streamline updates, and ensure that your domains resolve correctly. Whether managing root domains or multiple subdomains, using A records and CNAMEs appropriately helps maintain a reliable online presence.
Explore the tools and services that PowerDMARC offers to optimize your DNS configuration, streamline domain management, and enhance email security.
Frequently Asked Questions
Can you have a CNAME without an A record?
Yes. A CNAME record functions independently from A records because it directs users to another canonical domain, which will find its IP address through its own A record. However, the canonical domain needs to have an A record (or AAAA record for IPv6) to achieve proper resolution.
Can a CNAME and A record coexist?
No. The DNS protocol establishes a rule that prevents CNAME records from sharing the same name with any other DNS record type. The existence of a CNAME record for blog.example.com makes it impossible to add A, MX, or TXT records for the same domain. The system maintains clear resolution paths through this rule, which prevents record type conflicts.
Can a domain have multiple A records?
Yes. A domain name can contain multiple A records, which direct traffic to different IP addresses. The technique of using multiple A records enables organizations to distribute traffic between different servers for both performance improvement and system redundancy.
Is an A record better than CNAME?
A records provide the best speed for root domains, but CNAME records offer better management for subdomains. The answer varies based on your specific circumstances.
Domain & Email Security Expert at PowerDMARC
Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.
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