How do I flush my browser and DNS caches?

Complete the following steps.

1. Close your browser (Internet Explorer, Firefox, Safari or whatever browser you are using).

2. Flush your DNS cache. See the instructions at

https://support.opendns.com/entries/26336865-Clearing-the-DNS-Cache-on-Computers-and-Web-Browsers

3. Clear your browser cache. See the instructions at

http://www.refreshyourcache.com/en/home/

4. You may have a router or modem that also needs to have a cache cleared. Please check with your internet service provider on how to do this.

5. It's possible that Cloudflare (the service we use to guard against attack) is caching your website. Contact us and have us purge the Cloudflare cache.

You are running up against the vagaries of caching, described here: https://managewp.com/blog/types-of-web-cache As soon as you post anything to the web, it is cached a bunch of places, which you may or may not have control over. 

Caching is good. Without it, the web would be impossibly slow. That’s why news outlets and most of the rest of the internet use content delivery networks.

You have a couple of caches on your computer. Wordpress has some. CHCS and the hosting companies we use have some. Social media have their own (which is why you were getting different results from Facebook and LinkedIn). And anything you post will probably end up in the Wayback Machine on http://web.archive.org/ Want to see what your site looked like a year ago? They probably have it.

Think live radio. Once the broadcast goes out, if the producer recorded it, they can edit it for future use. But they cannot change any recordings someone may have made of the original broadcast.

So if you know that something you post is likely to change, do not link directly to it. Instead, make a page on your site that you can share with others, like programdoctor.com/my-document. On that page, make a link that looks like

My Document (version 1)

If you need to change it, give it a different name, like my-document-v2.pdf, and change the link to

My Document (version 2)

This works because caches generally expect HTML (web) pages to change, and they are set to expire in a certain period of time, generally something like three hours, so they check for a new version of that web page after that time. But caches assume that documents like PDFs never change. Which is why you need to give your PDF a different file name you change it, and give it a different link (and delete the old version). This way, the various caches will see the new version of programdoctor.com/my-document fairly quickly, note that its content has changed, and pull in the new document with a new name, like programdoctor.com/my-document-v2.pdf. 

Of course, you can get around the issue by never changing your original PDF. But nobody’s perfect, right?