DNS records, also known as "zone files", are used for mapping a URL to an IP address. These records are located on DNS servers, which are known as nameservers. When a URL is typed on a browser, the browser connects to a nameserver to find out where that URL actually points to, which may be a web server, email server or any other server. These servers serve the information requested in the URL, hence the name 'server'.
The simplest analogy is that of a friend's house. Consider John Smith, whom lives at 123 Fake Street, New Orleans. You know where John's house is and you know it by the name "John's house". But this information wouldn't tell anyone else how to get there; for that, they would need your address book. The address book is the nameserver in this analogy, and the DNS records are basically the information in that address book - they map "John's house" to "123 Fake Street, New Orleans".
Different types of records
The most commonly used records and a brief description of them is provided below. If you are interested in a more in-depth explanation of all the different types of DNS records, I recommend heading over here.
Mail Exchanger (MX) records 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 highest priority record, the second priority record is used, and so on. In other words, Mail Exchanger (MX) records tell the mail where to be delivered. If you aren’t receiving your email correctly, it's possible you have a problem with your MX records.
These are WebCentral’s MX records:
@ IN MX 10 mx1.bne.server-mail.com.
@ IN MX 50 mx2.bne.server-mail.com.
An A record (Address Record) points a domain or subdomain to an IP address. This record dictates what IP address your browser ends up at when you type in your domain name, so it’s imperative that it your A records are correct.
CNAME Records are a record that you will see cropping up all over the place. To be clear, the value of a CNAME record is always a domain name. Thus, CNAME records are often used to create subdomains. CNAME records are useful because they allow you to set up an alias to a server without using its IP address, through an intermediary standard domain name.
For example, www.example.com can have a CNAME record pointing to example.com. This way when you type in your browser www.example.com, you are actually redirected to example.com.
Text records are special in that they are not used to direct any traffic, as most other record types are. Instead they are used to provide information to outside sources. The most common uses for TXT records are Sender Policy Framework (SPF), DomainKeys (DK) and DomainKeys Identified E-mail (DKIM). TXT records historically have also been used to contain human readable information about a server, network, data centre and other accounting information.
TTL stands for Time To Live. Your TTL value sets the longevity of information served from your nameserver. When a DNS record is queried, the computer that initiated the query will hold onto that record for the time specified by the TTL. If the next query for that record occurs within that timeframe, it serves the answer from its own cache. Otherwise, it checks your nameserver again and obtains an up-to-date record.
TTL is always set in seconds.
Checking your current records
You can do this easily from your own computer, using a program called “nslookup”, meaning "name server lookup". Nslookup is a network administration command-line tool used for querying the Domain Name System (DNS). This command can be used via the command prompt on your computer.
1. Open Command Prompt (Start -> Run -> CMD -> enter)
2. Type the following command into the first line and press enter: nslookup –type=all
3. Great, you have now initiated a nameserver lookup of all records. You can now go ahead and type in your domain name and press enter again. This will then present you with your DNS records.
For a complete list of WebCentral's nameservers please head over to this article: WebCentral's Nameservers