SharePoint 2013 Best Practices: Tips for Troubleshooting Load Balancing

Adjust the SharePoint Master page on each WFE and add an HTML comment to it such as: <!—WFE 1 –>, and <!—WFE 2 –>.
(Expert note: Yes, I know that’s not supported in production, but if you don’t dare to try minor stuff like that when the situation calls for it, you’re just lacking courage ;-)!)