What is DNS - Domain Name System Explained

DNS or the Domain Name System (also referred to as Domain Name Servers) is like "the phone book of the Web". While a phone book helps you translate a name like “Acme Pizza” into the right phone number to call, the DNS translates a URL / web address such as www.example.com, or an email address such as [email protected] - into the correct server address.  

When you type in a web address, or send an email, your computer contacts the server that hosts that website or email in order to complete the sending or receiving of information.  This is sometimes referred to as a data transaction, or simply a transaction.  In this case, when you type up www.example.com, your computer "talks" to your Internet Service Provider, who in turn, talks to a localised DNS server hub, who in turn then communicates - or announces - where and how the data is stored (published) for that particular address enquiry.

In the case of a website, it is usually specified as an IP address e.g. 192.168.1.1.  In the case of email, the DNS usually specifies a particular mail server e.g. mail.example.com.  There are several records that make up the DNS - you can see a glossary of the terms in the footer of this article.

Once your device knows where the information is stored or hosted, a data transaction is then conducted with the published server address.  Data typically bounces off several computers / servers (satellites) before it magically appears on your screen.  All of this happens within milliseconds - because data transfer occurs at the speed of light (assuming no bottlenecks)! If you're a bit geeky, you may know that the speed of light is 186,282 miles 299,792 kilometres per second !!  Don't get me started about why your internet speed is so slow!!

So in summary, the DNS is "the glue of the internet" - a record or map of where everything is and it facilitates all of the data transactions.  The DNS database is a marvel of reliable ingenuity with a network of records held in various centralised locations and several 'master databases' that regularly cascade updates out to all of the world's satellite servers.  This synchronisation is occurring all of the time, all over the world, so that every machine (phone, laptop, computer, etc) knows where to look to transact any information. 

Whenever you change your email or webhosting provider, or make certain other changes to your domain name, it is necessary to notify the DNS database of the change, so that the incoming enquiries and requests get sent to the new address and not the old one.  Usually, these changes are notified automatically, whenever a change is made to your domain name.

As you can imagine, once a change has been notified, the DNS must be updated across the global network of DNS servers.  This can take as many as 2 or 3 days (and sometimes longer) to complete because the change must be communicated out to all of the world's DNS servers, from the central DNS database.  This is known as "DNS propagation" and many different factors can affect the speed at which propagation completes.

In most cases you should not need to make any changes to any aspect of your domain DNS because Purple Dog will usually handle all of this for you.  We are very experienced in these matters and strongly recommend that you consult with us first, should you wish to make any DNS changes.  If you do make changes to the DNS (or request us to do so for you), you should know that it can take between 1 and 72 hours for the changes to fully propagate across the internet and it is important to note the following:

IMPORTANT NOTE: When any DNS changes are made to your domain name, it can affect delivery of your email / website and any other connected services. You can experience slow data transactions and your email / website could experience interruptions.  If you have any doubts, please let us know prior to making any changes to you domain's DNS settings.

DNS Switch OverFor your convenience, here is a quick guide / Glossary to the different aspects of DNS.

Name Server Record (NS)

Name Server (NS) records determine which servers will communicate DNS information for a domain. Generally, you will have a primary and secondary name server record for your domain. If you are hosting your website or email at Purple Dog, your domain name will need to point to our Name Servers. Which one depends upon which hosting service you have purchased - please check the "Hosting Account Welcome Email" that was sent to you when you signed up, as these show will show the correct NS for your service. 

An example of the Purple Dog Hosting Nameserver is ns1.purpledog.info & ns2.purpledog.info

 

A Record

Address or "A records" (also known as host records) are the central records of DNS. These records link a domain such as “www.example.com” into the correct IP address to contact (for example “192.0.43.10”). 

 

MX Record

Mail Exchange (MX) records are part of the DNS - they direct email to servers for a domain. Multiple MX records can be defined for a domain, each with a different priority where the lowest number is the highest priority. If mail can't be delivered using the first priority record, the second priority record is used, and so on.  For example, you might have To set up email with Google Apps, you need to point your MX records to the Google mail servers first.

 

CNAME Record

Canonical Name or CNAME records link an alias name to another canonical domain name. For instance, alias.example.com might link to example.com. You'll need to use CNAME records if you want to configure a custom URL for specific services (such as Google Apps).

 

TXT Record

Text or TXT records may contain arbitrary text but can also be used to define machine readable text. TXT records are used primarily for domain ownership verification purposes. Also, you’ll need to use TXT records to implement email abuse prevention methods such as SPF, DKIM, and DMARC.  These all help to ensure that your emails will not get stopped by spam filters.

 

 

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