HTTP 301 Moved Permanently

Overview

The HTTP 301 Moved Permanently status code indicates that the requested resource has been permanently moved to a new URL provided by the Location header in the response.

Purpose

The HTTP 301 response is used to redirect clients to a new URL, indicating that the resource they are trying to access has been permanently moved to a new location.

Usage

Client Behavior:

1. Send Request: The client sends an HTTP request to a resource’s URL.
2. Receive Response: The client receives the HTTP 301 status code along with the new URL in the Location header.

Server Behavior:

1. Identify Moved Resource: The server recognizes the request for a resource that has been permanently moved.
2. Send Response: The server sends a 301 Moved Permanently response, providing the new URL in the Location header.

Scenarios

• URL Changes: When the URL of a resource (like a webpage or API endpoint) changes permanently.
• SEO Practices: To ensure search engines index the new URL and not the old one.

Sequence Diagram

Illustrating the process for an HTTP 301 response:

sequenceDiagram
    participant Client
    participant Server as Web Server

    Note over Client: Client requests an old URL
    Client->>Server: GET /old-page HTTP/1.1
    Note over Server: Server redirects to the new URL
    Server->>Client: HTTP/1.1 301 Moved Permanently
    Server->>Client: Location: /new-page

Curl Request and Response Example

Using Curl to request a resource that has been permanently moved:

curl -i http://example.com/old-page
# Expected response: HTTP/1.1 301 Moved Permanently
# Location: http://example.com/new-page

PHP cURL Request and Response Example

PHP script using cURL to handle a request to a URL that has been permanently moved:

<?php
$ch = curl_init('http://example.com/old-page');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
if (curl_getinfo($ch, CURLINFO_HTTP_CODE) == 301) {
    $newUrl = curl_getinfo($ch, CURLINFO_REDIRECT_URL);
    echo "The resource has been moved permanently to: " . $newUrl;
}
curl_close($ch);
?>

Python Request and Response Example

Python script to send a GET request and handle a 301 Moved Permanently response:

import requests
response = requests.get('http://example.com/old-page')
if response.status_code == 301:
    print("Resource moved permanently to:", response.headers['Location'])

Apache Configuration for HTTP 301 Moved Permanently

Configuring Apache to redirect a URL permanently:

<VirtualHost *:80>
    ServerName example.com
    RedirectPermanent /old-page http://example.com/new-page
</VirtualHost>

NGINX Configuration for HTTP 301 Moved Permanently

Setting up NGINX to handle permanent redirection of a resource:

server {
    listen 80;
    server_name example.com;
    location /old-page {
        return 301 http://example.com/new-page;
    }
}

HTTP 300 Multiple Choices HTTP 302 Found