Internet and networking information

These articles cover a variety of networking topics, from troubleshooting connectivity to clearing a browser’s cache.

Clearing a web browser’s cache and cookies

Occasionally, especially while you are creating or configuring your website, you might need to delete the cookies and cache from your web browser. This article explains how to empty the cache in several widely used web browsers.

Clearing the DNS cache on your computer

You may need to clear the DNS cache on your computer from time to time, particularly when you are developing or setting up your website. This article shows you how to clear your DNS cache in Windows, Mac OS X, and Linux operating systems, as well as in the Google Chrome browser.

Clearing a web browser’s SSL state

You may need to clear your web browser’s SSL state, particularly when you install a new SSL certificate. This article shows you how to do so with Mozilla Firefox, Microsoft Edge and Internet Explorer, Google Chrome, and Opera.

Introduction to network troubleshooting

As a web site administrator, you may need to troubleshoot network issues from time to time. This article provides an introduction to basic network troubleshooting concepts — learn about some of the troubleshooting tools you can use, and when to use them.

Troubleshooting network connectivity using ping and traceroute

You can use a ping test and the traceroute and MTR tools to troubleshoot network connectivity to a remote host, and this article demonstrates how.

Testing DNS with dig and nslookup

You can use the dig and nslookup tools to troubleshoot DNS settings for a domain. This article demonstrates how to use both web-based tools and command-line tools.

Troubleshooting network applications with telnet

Although SSH is now used for secure connections to servers, the telnet program is still valuable as a troubleshooting and diagnostic tool. In this article, learn how to use it to troubleshoot web servers, mail servers, FTP, and SSH.

Troubleshooting SSL connections with the openssl program

Learn how you can use the openssl command-line program to help troubleshoot SSL connections. This article covers how to install openssl, establish SSL connections, and troubleshoot SSL certificates, HTTP connections, IMAP connections, and POP connections.

Web pages display incorrectly on mobile devices

Web pages may not display correctly on some mobile devices. Learn why this problem occurs and how to resolve it (by either setting the Cache-Control header in PHP or in a .htaccess file) in this article.

Backscatter and spam

Learn what backscatter is and some ways to help reduce it in this article.

Checking your website for broken links

Learn how to check a website for broken links (URLs). This article shows you two methods of checking links by using either Google Search Console or the W3C Link Checker.

Troubleshooting network applications with curl

The curl program is valuable as a network troubleshooting tool. Learn how to use it to troubleshoot web servers, mail (SMTP) servers, FTP, and SSH in this article.

Troubleshooting network applications with PowerShell and tnc

The tnc program in PowerShell is valuable as a network troubleshooting tool. Learn how to use it to troubleshoot web servers, mail (SMTP) servers, FTP, and SSH in this article.

Troubleshooting nameserver errors

DNS errors related to nameservers can cause your site to be unavailable. Learn to fix errors, particularly missing nameservers reported by parent, SOA MNAME entry, and missing nameservers reported by your nameservers, with this article.

Off-shore IP addresses

Sometimes, an IP address’s geolocation inaccurately displays a location far from where the hosting server is physically housed. Learn why in this article.

Google Chrome error message: “ERR_QUIC_PROTOCOL_ERROR”

This article describes a problem that may occur when you browse the internet using Google Chrome, as well as several ways to resolve it.

Setting up a Wi-Fi hotspot on your mobile device

You may need to test something on a network outside of your regular home or office network. To do this, you can set up a Wi-Fi hotspot on your mobile device that enables you to use the cellular data network. This article shows you how.

Clearing the DNS cache on macOS

You may need to clear the DNS cache on your computer from time to time, particularly when you are developing or initially setting up your website. This article shows you how to clear your DNS cache on computers running Apple’s macOS or Mac OS X.

Changing your DNS provider to reduce DNS propagation delays

When you change the name servers for your domain, DNS propagation can take 24 hours to complete. Learn how to reduce this propagation delay by switching DNS providers on your computer.