Domain Name Server (DNS) Management Guide
This article will explain about Domain Name Servers and what they do.
What is a Domain Name Server (DNS)?
DNS stands for Domain Name System. The main function of DNS is to translate domain names into IP Addresses, which computers can understand. It also provides a list of mail servers which accept Emails for each domain name. Each domain name in DNS will nominate a set of name servers to be authoritative for its DNS records.
This is where all other name servers will be pointed when looking for information about the domain name. Name servers are a program or computer server that implements a name-service protocol. This is where the zone file is stored and your DNS records are stored within. A zone file is a small set of instructions that points domain names to IP addresses.
A zone file is made up of ‘records’ such as A Records and MX Records. This record is used to point your domain name to an IP address. If you need to set up a A record, your provider would provide you with an IP address that will look something like 18.104.22.168. If you need to set up a CNAME record, your provider would provide you with a URL address that will look something like web.me.com. This is used to specify which mail servers are responsible for a particular domain name.
One special MX Record feature is priority numbers, which provide information to the querying mail server about which mail server should be used first. The next entry is tried only when the mail server with the highest priority is not available.
What are cached DNS records?
To speed up DNS most name servers on the internet will cache (remember) DNS records themselves so that they do not have to look up records each time they require them.
When you visit a website, it is probable that your ISP’s name servers will remember the IP Address, so that the next time you (or someone else) requests that website, the IP address can be retrieved more quickly. In this instance, your ISP’s name server is using a cached DNS record. It will use this cached record for a period of time, after which it will retrieve the record again. It will again cache the record and the cycle will repeat.
This is why when you make changes to your DNS some people will not see the change immediately as they may well be seeing a cached record.
What are subdomains?
A subdomain is a subdivision of a domain name, allowing you to put content in your URL before your namespace. For example, blog.companyname.com or shop.companyname.com would be a subdomain of the domain name companyname.com.
For example: If a customer buys a domain with 123 Reg, e.g. yourdomain.co.uk, they can set up subdomains, e.g. site1.yourdomain.co.uk or secure.yourdomain.co.uk. This is an excellent way of breaking up the website if you have different regions, products or even languages.
What are nameservers?
A nameserver maintains a directory of domain names that match certain IP addresses. In other words, it’s where the DNS server records for your domain are stored, allowing you to decide which hosting providers controls your webspace and email. All domain registrars should provide you with the ability to change at least two nameserver entries on your domain name, and hosting companies should offer you at least two nameservers to point to.
One of the advantages of registering your domain name with 123 Reg is that you are free to change the nameservers to other hosts whenever you like. However, if you choose not to point to our nameservers, you won’t be able to use our web and email systems to configure your domain name, nor will you be able to use our hosting solutions.
Read our other article if you would like to find out more about 123 Reg nameservers.
Please note: If you change the DNS to another registrar, you will no longer be able to configure your DNS changes for that domain within your 123 Reg control panel.
How to check nameservers
The simplest way to check the nameservers your domain is on is to go to http://who.is/, type in your domain name into the box and click on the lookup button. This will show you a section that lists your nameservers.
How to change nameservers
You can change the nameservers of your domain name from the 123 Reg control panel. Check out our useful guide for step-by-step instructions.
How to set up an A record
The A (Address) record is used to point your domain at an IP address. To set it up, you will need an IP address from your provider. Please refer to our guide for complete instructions on how to set up an A record.
How to set up a CNAME record
Our support guide includes all the steps you need to follow to set up a CNAME (Canonical Name) record. Keep in mind that you will first need a URL address such as web.company.com from your provider.
How to set up a TXT record
A TXT (text) record is used to hold some text information. You can put virtually any free text you want within a TXT record. A TXT record has a hostname so that you can assign the free text to a particular hostname/zone.
The most common use for TXT records is to store SPF (sender policy framework) records and to prevent emails being faked to appear to have been sent from you. A TXT record is commonly used to store what is called SPF (Sender Policy Framework) data. SPF data controls which IP addresses and servers are allowed to send e-mail from your domain so it is used to combat spam.
For example, you could set up a TXT record on mywebsite.com that contains the internet IP address of your computer at home, this would mean that mail claiming to be FROM: firstname.lastname@example.org is only allowed to come from your home IP.
Anyone else trying to send mail as FROM: email@example.com would be rejected, because the IP address of the computer they are sending from is not contained in the TXT record. TXT records can also have other uses such as verification for Google Apps or Microsoft Office 365.
How to set up an SPF record
A Sender Policy Framework (SPF) record is used for identifying which mail servers are allowed to send email on behalf of your domain. The main purpose is to prevent spammers from sending emails with forged From: addresses at your domain. For detailed information on how to set up an SPF record for your domain name, please refer to our support guide.
How to set up an MX record
A Mail Exchanger (MX) record specifies which mail servers are responsible for a specific domain name. Download our guide for more information and to learn how to set up an MX record.
What is domain propagation?
DNS propagation (or Domain Name Propagation) is a term to describe the updating of information across the Internet. It takes two forms: changes to your DNS Zone and changes to your WHOIS information. A change to your DNS Zone information typically affects only a handful of servers and completes much more quickly.
However, the WHOIS is the master record which tells every DNS server in the world the server for your domain. A change to your WHOIS information (such as updating the ADMIN-C in your control panel) can take up to 72 hours to propagate fully. Customers often call the 123 Reg support centre to say that they can’t see their domain names straight after ordering them, or just after a transfer between providers.
After either of these two events, your domain name/website may not be visible for up to 48 hours, mainly because millions of DNS servers need to be updated with the new information.
What is TTL, and what is it used for?
TTL stands for Time To Live, and measures the lifespan of data in a computer or network, for example, when you create an SRV record for your domain name. This dictates the length of time it takes for the cache of the server to update, so if you make a change, this is the length of time it will take the propagate. TTL is measured in seconds, so, for example, a TTL of one hour would equate to a TTL to 3600 seconds.
Please note: When you create records for your domain names through 123 Reg, the TTL is automatically set at 14400 seconds, which equates to 4 hours, and cannot be changed manually.