Francesco Altomare
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10967 Berlin (Germany)
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DNS: The Basics #1

What is DNS and why should you know about it?

Imagine that everyone was known by numbers. Our friends will have numbers like 29 or even 118659558. You may even have to call your partner 1100100. It would be a tough world – remembering numbers. Aren’t we fortunate that people have names instead of numbers? It’s the same for our website or any other site for that matter. But there is a huge problem. Computers and networks don’t understand names at all, they only know numbers. They are more comfortable with numbers and that’s why they are called machines. To bridge or resolve this problem DNS has been created a kind of man-machine interface.

What’s DNS really?

DNS or Domain Name System is a tool which converts human friendly names of websites into computer friendly numbers. To put it in technical terms, DNS is a protocol which translates names into numbers. This is achieved through a database which resides on a server. This database maps the real world names into numbers called IP addresses. The server which contains the database is called the Domain name server. We will learn more about IP addresses and name servers as we go along.

Why should we as a business person, know about DNS?

There are many technical issues which businesses are never concerned about and most don’t really effect day to day operations. But, DNS is a different cup of tea, altogether. To give a small example, a DNS outrage at a big hosting company caused a loss of $50,000 in sales to an online retailer. This was reported in here. Technically it was an outage- that’s how the technical people call it and that too with an impassive face, as if nothing happened, while your house is burning or burnt down. That’s why business persons are wary of technical guys. Let’s say that it’s always prudent to take precautions. No point in firefighting, when it’s too late. If you think that you can go to a big name in DNS and forget about the rest ……. wish it were as simple as that.
Therefore it is essential to understand the dynamics or working of DNS. There are four issues which must concern us while choosing a DNS provider.

  1. The first is directly related to the activities of the provider. Is DNS the core competence of the provider or it’s just another service provided by them? In this respect we have to closely examine the track record of the provider.
  2. Availability is an important factor which would determine your final choice. Uptime is crucial, more so when we are an online entity. Even a downtime of an hour can be devastating. The SLA of the provider must be closely scrutinized.
  3. The third factor is the performance. How quickly is the server able to resolve DNS queries will affect user experience? We often get fed up and move on when a particular website takes ages to load. This means lost opportunity for the website. A DNS server must be able to quickly resolve addresses. We will look into factors which are related to availability later.
  4. Security is by far the most important factor when considering a DNS service provider. In the article cited above, one of the reasons for the outage was a DDoS attack. With the proliferation of devices like mobiles and tablets, the issue of network security is becoming complex. Needless to say that security forms a large part of the DNS apparatus. There can be numerous reasons why a DNS server may encounter problems. Configuration is a factor which often causes outage.

How does DNS work?

The internet, as we know it, consists mainly of websites and email addresses. Users can access website by typing its name followed by an extension like .com, .org etc. These extensions were earlier restricted to twenty two. Now, The Internet Corporation for Assigned Names and Numbers (ICANN) has increased the list and we may have as many as one thousand four hundred extensions in the near future. This has immediate repercussions on your website business. You must keep a lookout for these new domains and book yours before your competitor. Coming back to DNS and the link with your website or domain name, you must understand that there can be no internet without a process which translates names into numbers. Let’s examine how DNS server crunches the numbers.

How does DNS resolution happen?

Before we begin, let’s understand what is an IP address? Can you recognize Most of us can. This is an IPV4 standard where each of the three digits is an octet. Therefore we can have only 256 combinations of these groups. Lately, the number of unique combinations which we can get from this grouping seems to be insufficient to meet the demand. A new standard IPV6 has been introduced which eight hexadecimal numbers has separated from each other with a colon. We will deal with this topic in detail later.
A name server or DNS server has a record or database of all these IP addresses and also of the actual website names. When, you type a name like in the address bar of the browser, the name gets transmitted to a name server. This in turn converts the names to an IP address. This IP is now traced to the web server in which your website is hosted. The web server displays the site on your browser. You can ask whether it is possible to type the IP address directly in the address bar. Yes, of course, you can. There are hundreds of DNS servers. The next obvious question is which DNS server you will be using.

What is a DNS Zone?

There are thousands and millions of domain names and each one of them has to be resolved. Every DNS server cannot have all the records or database of every domain name. To make things simpler, the entire DNS has been divided in zones. What happens if the zones fail? Due to this reason zones are replicated in other DNS servers as well. Zone transfers are initiated when they are replicated into other zones. At this juncture, it’s enough to know why zones are required.


We can safely assume that knowledge of DNS is not only important but also critical for your business. Your DNS provider must be able to provide services consistently and must be able to resolve DNS quickly. In the next post we will learn about most important records SOA, A, CNAME, MX, NS etc.

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