Apache或PHP将我的URL重写为IP地址

I have a PHP/HTML5 app that requires an application.ini file parse the URL to determine a usage path. The DNS is configured correct, but when I attempt to hit the page I see that the domain name is being dropped and instead application.ini "sees" the ip address instead. I get the error:

PHP Fatal error: Uncaught exception 'Zend_Application_Resource_Exception' with message 'no domain settings for 555.16.8.69' in /var/www/html/library/<app>/Application/Resource/Domainsettings.php:63
Stack trace:
#0 /var/www/html/library/Zend/Application/Bootstrap/BootstrapAbstract.php(683): Application_Resource_Domainsettings->init()
#1 /var/www/html/library/Zend/Application/Bootstrap

Where did the domain name go? I don't think my rewrite rules are doing anything strange:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

The real problem comes in a DomainSettings.php file with this line: $this->getHost();

If you can't tell, I didn't write this code. I am attempting a port.