A CNAME record is a DNS alias that points one hostname to another hostname. Instead of resolving directly to an IP address, the queried name follows the alias and inherits the destination name’s resolution. This is common for branded subdomains, cloud services, and content delivery platforms because it lets administrators change the underlying service without changing every public hostname.
In cyber security, CNAME records matter because they can outlive the service they reference. If a cloud app or third-party service is removed but the CNAME remains, the hostname may become a dangling record. In some provider environments, that can enable subdomain takeover if another party can claim the target namespace. Defenders reduce this risk by inventorying CNAMEs, removing stale aliases during decommissioning, and checking provider-specific takeover conditions as part of DNS hygiene.