DNS Settings
This section contains essential information about making DNS changes to your web site. Please read this document thoroughly. Topics include an important message for beginners, a short DNS tutorial, an explanation (with examples) of: A, CNAME, NS, and MX records, and how to change DNS settings.
Important Message for Beginners
The ability to change the DNS configuration of a web site is an important feature for many people. However, incorrect DNS modifications can take an entire web site and associated email addresses down for an extended period of time. This is because DNS changes aren't instant (see the Tutorial below). If you make a mistake, it is possible that nobody will be able to connect to your site (including yourself). Even if you fix the mistake, it may take up to 48 hours for the repair to take full effect.
There are several things you can do to prevent mistakes:
1. Read this document thoroughly.
2. Make sure you understand what A, CNAME, NS, and MX records do.
3. Contact your Seanet's DNS Administration for additional help and guidance.
4. Don't make a major change without assistance.
With a little bit of practice, you will find that making DNS changes is very simple.
DNS Fundamentals
DNS (Domain Name Servers) tell computers how to find each other over Internet. When you type an address in your browser, your ISP (Internet Service Provider) checks with it's domain name server (DNS) to determine where to send you.
http://www.domain.com ---> Check with DNS ---> DNS says domain.com = 192.168.0.1 ---> You are taken to web site.
Why does this happen?
It happens because your domain name won't always have the same IP address. Each server on the Internet has an IP address (a numerical address like a phone number). Every time you change web hosts, you are changing servers (and therefore changing IP addresses).
Domain name servers keep a record of your domain name and what IP address (server) it should point to.
Why must I put my web host's name servers (DNS) in my domain record?
As you learned above, name servers tell the Internet how to find you. When you edit the name servers in your domain record, you are telling the Internet which name server provides the most up-to-date directions. If you don't change the name servers in your domain record (let's say you use your old web host's DNS), then your web site will point to a server that isn't hosting your domain. Or, if the old web host deleted you from their DNS, your domain wouldn't work at all.
Why does it take so long for my site to start working?
When you change web hosts (addresses) or register a domain for the first time, the new DNS information has to reach every other name server (DNS) on the Internet. Your site may work in as little as a few minutes, but the average waiting time is 24+. This delay occurs because name servers (DNS) are designed to cache information for a specific length of time (TTL - usually 24 hours) and will only check for an update after the specified TTL for the record has expired. Periodic checking is done because constant checking would slow down a DNS server and cause unnecessary traffic.
Why is my domain pointing to my old host, even though I cancelled my account with them?
There could be several reasons for this:
1. Their name servers are still in your domain record.
Solution: Update your domain record to list Seanet's name servers (DNS1.seanet.com and DNS2.seanet.com).
2. They haven't removed your domain record from their name servers.
Solution: Ask them to remove your domain record.
3. DNS propagation hasn't taken place yet. This may happen even if Seanet's DNS servers are listed in your domain record.
Solution: Wait 24-48 hours and contact Seanet's DNS Administration if the problem persists.
Why can some people reach my new site but I can't?
Their computer is accessing a more up-to-date DNS record than yours (Individual computers will often cache DNS data internally. If you suspect this might be the problem you could try to reboot your computer). Be patient, as your new site will appear within 24-48 hours.
Is there some way to view/access my site even though the DNS hasn't changed yet?
Yes. You may access your site at http://control.seanet.com/~username
Changing DNS Settings
At the main control panel menu, click the "DNS Management " to access the DNS settings.
Above is an example of the DNS settings for a fictitios domain, demo.com. The next sections provide information on changing A, CNAME, NS, MX, and PTR records. In the meantime, it is important to understand how the control panel handles hostnames.
Important: There are two ways to enter a hostname:
1. The full hostname followed by a period: full.hostname.com.
2. The subdomain alone: full
For example, the www record in the table above could be specified as:
www A 64.38.170.21
or
www.demo.com. A 64.38.170.21
Both records do the exact same thing. The sections below may discuss only one method but either is acceptable.
Hint: If you are unsure how to enter a record, look at the existing records in the table for guidance.
Records Explained: A, CNAME, NS, MX, and PTR.
A RECORDS
Address (A) records direct a hostname to a numerical IP address. For example, if you want mycomputer.yourdomain.com to
point to your home computer (which is, for example, 192.168.0.3), you would enter a record that looks like:
Important: You must put a period after the hostname. Do not put periods after IP addresses.
CNAME RECORDS
CNAME allows a machine to be known by one or more hostnames. There must always be an A record first, and this is known as the canonical or official name. For example:
yourdomain.com. A 192.168.0.1
Using CNAME, you can point other hostnames to the canonical (A record) address. For example:
ftp.yourdoman.com. CNAME yourdomain.com.
mail.yourdomain.com. CNAME yourdomain.com.
ssh.yourdomin.com. CNAME yourdomain.com.
CNAME records make it possible to access your domain through ftp.yourdomain.com, mail.yourdomain.com, etc. Without a proper CNAME record, you will not be able to connect to your server using such addresses.
Entering a CNAME record
If we wanted home.site-helper.com to point to site-helper.com, we could enter the record in two ways:
The first method allows you to simply enter the subdomain. Do not put a period after the subdomain name.
The second method requires you to enter the entire hostname, followed by a period.
NAMESERVER (NS) RECORDS
NS records specify the authoritative nameservers for the domain.
Important: Changing NS records may cause your site to stop working. There is generally no need to change NS records.
Entering a NS record
The first step is to delete the old NS records from the table above.
Then, enter two new nameservers records. Be sure that the nameserver hostname is followed by a period, as in this example:
Be sure to put a period after the nameserver hostname in a NS record (ns1.newnameserver.com. and not
ns1.newnameserver.com ).
MX RECORDS
If your email is to be handled on a remote server, your MX changes be made in order for their software to work. This change allows mail destined for your domain to be directed to their server.
Important: Changing MX records may prevent your current POP3 accounts, forwarders, autoresponders, and mailing lists from functioning. If you are unsure on how to setup your MX records, please contact our DNS Administration Department before making any changes.
To change MX records, click on the "MX Records" link on the main control panel page. (Note: MX records can also be modified from the main DNS panel)
Unless your account has already been customized, you will initially see a default MX configuration as above.
The MX "Value" entry determines the priority of the server listed. Mail will always be delivered to the highest priority server (lowest MX value) first and will only go to a lower priority server if necessary.
The default configuration is setup so as to have a backup mail spool ( smtpgate.seanet.com. ) with MX 20.
To change your configuration, delete the old MX record(s) by clicking the checkbox to next to the record name and click "Delete Selected."
Next, type in the hostname, followed by a period, given to you by your e-mail provider. Then select the priority level (usually 10) from the dropdown box on the right. The priority level will also be given to you by the e-mail provider. Click "Add."
Repeat this process for any additional MX records required.
Note: Be sure to put a period at the end of the hostname.
To restore the original MX settings, enter mail.yourdomain.com. and priority 10 after deleting the other MX records.
PTR RECORDS
Pointer records (PTR) are used for reverse lookups. If your hosting plan has its own dedicated IP address, you may request a custom PTR record be setup for it by emailing our DNS Administration Department.
Need more help?
If you need further assistance with any Control Panel feature, please contact our Customer Support department.
Helpful information is also available in the
DirectAdmin support forums.
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