When migrating from xy.example.com to abc.example.com, we need to implement a permanent redirect (HTTP 301) that preserves the entire request path. This means:

http://xy.example.com/team.php → http://abc.example.com/team.php
http://xy.example.com/blog/post → http://abc.example.com/blog/post

There are two primary methods to achieve this in Apache:

Method 1: Virtual Host Configuration

The most efficient approach is to configure this at the virtual host level:

<VirtualHost *:80>
    ServerName xy.example.com
    Redirect permanent / http://abc.example.com/
</VirtualHost>

Key points:

• Redirect permanent sends a 301 status code (better for SEO than temporary redirects)
• The trailing slash after the domain ensures path preservation

Method 2: Using .htaccess

For situations where you can't modify the main config:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^xy\.example\.com$ [NC]
RewriteRule ^(.*)$ http://abc.example.com/$1 [L,R=301]

After implementing, verify with:

curl -I http://xy.example.com/team.php

You should see:

HTTP/1.1 301 Moved Permanently
Location: http://abc.example.com/team.php

For HTTPS redirects:

<VirtualHost *:443>
    ServerName xy.example.com
    SSLEngine on
    # SSL certificates here
    Redirect permanent / https://abc.example.com/
</VirtualHost>

To handle both www and non-www versions:

RewriteCond %{HTTP_HOST} ^(www\.)?xy\.example\.com$ [NC]
RewriteRule ^(.*)$ http://abc.example.com/$1 [L,R=301]

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When migrating from an old domain (xy.example.com) to a new one (abc.example.com), it's crucial to maintain URL structure integrity. This means:

• Root domain requests should redirect properly: xy.example.com → abc.example.com
• Path preservation: xy.example.com/team.php → abc.example.com/team.php
• Query parameters should carry over: xy.example.com/search?q=test → abc.example.com/search?q=test

Option 1: Using VirtualHost with RewriteEngine

<VirtualHost *:80>
    ServerName xy.example.com
    ServerAlias www.xy.example.com
    
    RewriteEngine On
    RewriteCond %{HTTP_HOST} ^(www\.)?xy\.example\.com [NC]
    RewriteRule ^(.*)$ http://abc.example.com$1 [L,R=301]
</VirtualHost>

Option 2: Using Redirect Directive

<VirtualHost *:80>
    ServerName xy.example.com
    Redirect permanent / http://abc.example.com/
</VirtualHost>

Key differences between these approaches:

Method	Path Preservation	HTTP Status	Flexibility
RewriteRule	Yes	301	High (regex support)
Redirect	Only root	301	Low (simple cases)

After implementing the redirect:

1. Restart Apache: sudo systemctl restart apache2
2. Test with curl: curl -I http://xy.example.com/team.php

Expected response headers:

HTTP/1.1 301 Moved Permanently
Location: http://abc.example.com/team.php

For complex redirect needs, consider these additional parameters:

RewriteRule ^(.*)$ https://abc.example.com$1 [L,R=301,NE,QSA]

Where:

• NE: No escaping of special characters
• QSA: Query string append
• R=301: Permanent redirect (SEO-friendly)

For HTTPS redirection, modify the target protocol:

RewriteRule ^(.*)$ https://abc.example.com$1 [L,R=301]

Or configure separate VirtualHost for port 443 with SSL certificates.