HTTP and DNS are protocols serving different purposes, and redirection via these two methods is fundamentally different.
DNS Redirection: DNS doesn’t inherently support redirection; it’s simply responsible for translating domain names to IP addresses. A form of redirection can be achieved in DNS by using CNAME records, which essentially make one domain name an alias of another. When a client requests the IP address for a domain, and the DNS server sees a CNAME record, it provides the IP address of the target domain instead. However, the client’s browser still displays the original domain in the address bar.
DNS changes happen at a low level in the network stack, even before an HTTP connection is established. However, it’s not a “redirect” in the true sense, and can’t be used to redirect from an apex domain to a www subdomain (because CNAME records are not allowed for apex domains due to DNS protocol specifications).
HTTP(S) Redirection: This is the real form of redirection that users commonly experience. When a client makes an HTTP request to a server, the server can respond with a 3xx status code and a “Location” header indicating a new URL. The client’s browser will then make a new HTTP request to the URL provided. Unlike DNS redirection, HTTP redirection can change the URL displayed in the client’s browser.
HTTP redirection happens after the DNS resolution and the establishment of an HTTP connection. It’s more flexible than DNS redirection, allowing for redirection between different paths, not just domains.
When to use each largely depends on your needs:
DNS “Redirection” (aliasing): Useful for simple domain aliasing where you don’t need to change the URL displayed in the browser, or when you want to point multiple domain names to the same IP address. However, it’s not technically a redirection and has limitations due to DNS protocol rules.
HTTP(S) Redirection: This is the method to use when you need to redirect users from one URL to another, such as from an apex domain to a www subdomain, from an old web page to a new one, or to redirect users to a secure HTTPS version of a site. It’s more flexible and is the correct method for most web redirection needs.
It’s important to note that improper redirection can lead to issues such as infinite redirect loops or search engine indexing problems, so it’s crucial to understand and correctly implement the type of redirect that best suits your needs.