Internet and networking information
These articles cover a variety of networking topics, from troubleshooting connectivity to clearing a browser's cache.
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Clearing a web browser’s cache and cookies
You may need to clear your web browser's cache and cookies from time to time, particularly when you are developing or setting up your web site. This article covers how to clear the cache on a number of popular web browsers.
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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.
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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 Internet Explorer, Google Chrome, and Opera.
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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.
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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.
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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.
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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.
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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.
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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.
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Backscatter and spam
Learn what backscatter is and some ways to help reduce it in this article.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 setting up your website. This article shows you how to clear your DNS cache on computers running Apple's macOS or Mac OS X.
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Changing your DNS provider to reduce DNS propagation delays
When you change the name servers for your domain, DNS propagation can take as long as 24 to 48 hours to complete. Learn how to reduce this propagation delay by switching DNS providers on your computer.