TABLE OF CONTENTS
- DNS Basics and Tools
- Email Basics and Tools
- Tools for Domain Names
- Tools for IP Address Lookups
- General Diagnostics Tools
- Speed and Performance Testing
As a reseller, you will become acquainted with a number of tools, each absolutely useful in their own right. Many of these tools have been designed to simplify the process of diagnosing issues, such as DNS related problems or to trace email delivery issues.
This is an incredibly short list, but we definitely recommend having them under your belt!
DNS Basics and Tools
DNS is a complex area of hosting - its one area where many people struggle.
You can read more about DNS here…
Computers address each other with numbers called IP addresses. However, remembering IP addresses is not an easy task for humans, who prefer to give things a name. DNS is a useful system that ties names to IP addresses.
DNS automatically converts the names we type in our web browser address bar to the IP addresses of web servers those specific sites requested. Therefore, when you enter a domain name, (e.g. google.com) your computer will find your nearest DNS server and ask it what the correct IP address is for that name. Then, the DNS will return the IP address and your computer can then address the relevant machine and display the requested website.
DNS whilst complex, works as follows...
The user logs onto their Internet Service Provider (ISP) to use the Internet.
The user opens up a web browser (Firefox, Chrome, Internet Explorer, Safari, etc.) and types a URL into the address bar. For example, perhaps the user types in https://brixly.uk
The computer then asks for the ISP’s DNS servers for the specific IP address for brixly.uk
Once the DNS server that holds this specific IP address for brixly.uk is found, the DNS server responds with the appropriate IP address and the user’s computer then gives this address to the user’s browser.
The browser opens a connection to the server using the IP address provided and retrieves the page from the site requested, in this case for brixly.uk
The browser displays the requested page on the computer screen.
DNS records are served from Nameservers - whilst this is a topic alone, a nameserver is essentially a machine responsible for storing, and returning the IP address to the browser.
Root name servers are another type of name server, which sits on the servers at the ‘root’ of the domain name system hierarchy, such as the following...
The root servers contain the information that makes up the root zone, which is the global list of top level domains. The root zone contains:
• generic top level domains – such as .com, .net, and .org
• country code top level domains – two-letter codes for each country, such as .uk
• internationalized top level domains – generally equivalents of country code top level domain names written in the countries’ local character sets
For each of those top level domains, the root zone contains the numeric addresses of name servers which serve the top level domain’s contents, and the root servers respond with these addresses when asked about a top level domain.
We then have ‘resolvers’, such as the ‘Google Public DNS’ on IP 188.8.131.52, 184.108.40.206 which are responsible for looking up the root resolvers above, to then find the authoritative nameservers for a domain. The browser then uses this trail to find the correct IP address for a domain name.
Whilst this all can sound a little complex (and to be completely honest, is!), you don’t need to know fully or understand the above in significant enough detail as there are tools which can help diagnose issues with DNS.
The basics you need to understand are the following pointers…
Domain Names have assigned ‘name servers’, which are allocated at the domain registrar for that particular domain.
The nameservers set at the registrar should have ‘Zone Files’, which are essentially files containing the ‘mapping’ of domain to IP address - these zone files are created automatically by WHM and cPanel for your clients
The DNS Zone itself contains ‘NS’ records, which should match the nameservers set at the root name servers
Because of the ‘flow’ of DNS, and the numerous locations where DNS is stored / cached, such a thing exists called ‘propagation’ - this is a term used by hosting providers which explains a ‘delay’ in DNS resolutions taking place.
Please note however, this is a term seemingly thrown around far too often. DNS propagation nowadays is pretty fast, and generally doesn’t take 24 - 48 hours as most people would suggest. The delays in this process however tend to be caused in most cases by heavy caching at your internet service provider, so DNS lookups can seem slower to propagate.
In this case, you can change your local machines ‘resolvers’ - this basically allows you to bypass your internet service providers nameservers (which will be cached fairly heavily), and instead use alternative resolvers for DNS lookups.
This is a must when dealing with hosting clients, to ensure the information you provide your clients is accurate - DNS propagation can cause delays in finding the ‘actual’ cause of a problem, so its always recommended when dealing with domains on a daily basis to ensure you use a faster resolver service, such as Google Public DNS or the Cloudflare ‘220.127.116.11’ service.
We have a guide on how to set this here…
If you have recently updated your domain name to use new DNS records, or have updated your nameservers entirely, then you can check the propagation status using the following website…
If you are looking to verify DNS records, then the following tools are ideal…
As you can see, DNS itself is a broad topic, definitely worthy of some research. There are hundreds of videos and explainers online which make DNS understandable. DNS is also covered in the cPanel university guides too!
Email Basics and Tools
Email, believe it or not, can be as complex (if not more complex than DNS!). Diagnosis of email related issues starts with understanding ‘where’ the issue exists. For example,
Is this an ‘inbound’ issue, or ‘outbound’?
Is the issue isolated to a particular domain in either of the above cases?
Is this only an issue with an email client, such as Outlook or is it an issue server-side?
Is this an issue with a message being flagged as SPAM, or is it just not sending at all?
There are many questions to ask when attempting to diagnose mail related issues, although the above is certainly a good starting point! When you have those details, you can make use of some of the tools available to you.
WHM also offers a great tool for checking the mail logs on a server, which can be found within WHM -> Delivery Reports
The full documentation on the Delivery Reports interface can be found here…
Additionally, there is an option within cPanel that is available to your clients called ‘Track Delivery’, which offers similar functionality to the above. The documentation for this can be found here…
Tools for Domain Names
DNS Lookups - https://dnslytics.com/whois-lookup
DNS Health Check - https://intodns.com/
DNS Propagation Checker - https://dnschecker.org/
Alexa Rankings - https://www.alexa.com/
SPF Checker - https://dnslytics.com/spf-lookup
Tools for IP Address Lookups
IP Address WHOIS - https://dnslytics.com/whois-lookup/
Geo Location for an IP address - https://dnslytics.com/ip-geo-location/
Blacklist Checker - https://mxtoolbox.com/SuperTool.aspx?action=blacklist:
General Diagnostics Tools
Ping Checker - https://network-tools.com/
Traceroute Checker - https://network-tools.com/
Blacklist Checker - https://mxtoolbox.com/SuperTool.aspx?action=blacklist:
SSL Checker - https://sslshopper.com/ssl-checker.html
SSL Security Check - https://www.ssllabs.com/ssltest/
Speed and Performance Testing
OK, before we start - it's important you understand the best methods for diagnosing site loading performance, as some tools can be deceiving. Some online tools provide a ‘score’, as opposed to just a loading time, such as Google Pagespeed (not a particularly trustworthy method of diagnosis, if you ask us!)
One of the most reliable, consistent benchmarking providers is the following…
Be sure though when testing, to select the server closest to the server where the site is hosted.
https://gtmetrix.com/ is also a fantastic tool for diagnosing performance issues on a site.