Frequently Asked Questions

DNS

Miscellaneous

Summary

Frequently Asked Questions - DNS

What is an IP address?

(Summary)

The Internet Protocol (IP) is a communication system that enables networked computers to exchange information.

For a computer to be able to reach another one on Internet, it must know its number (IP address).

A domain name enables the association of words (easier to remember) to an IP address. The worldwide domain names system is thus like a directory.

To be included in htis directory, you need to register your domain name with an ICANN accredited Registrar (http://www.icann.org/registrars/accredited-list.html), like Gandi.

What is a domain name?

(Summary)

It is a collection of letters separated in two parts:

the name (in our case: "gandi")
the TLD (in our case: "net")

Both parts are separated by a point. Which gives in our case: "gandi.net"

TLD means Top Level Domain : it is the final part (or extension) of the domain name. There are generic (worldwide) TLD (.com, .net, .org, .biz, .info, .name) and country code TLD (one per country, like .uk for United Kingdom).

To see TLD provided by Gandi, please have a look at http://www.gandi.net/tlds.html.fr and our News section.

What is a DNS?

(Summary)

The DNS acronym means two distinct things;

Domain Name System : the worldwide system that enables association of a name to the IP of a given computer
Domain Name Server : one of the computers that take part in this system.

We use here DNS to mean a nameserver (Domain Name Server).

What is the DNS used for?

(Summary)

It enables to convert a website name (like "www.gandi.net") to an IP address (like "212.73.209. 246").

A DNS must be able to reply to queries like that at all time. Thus it needs to be correctly configured, and to be connected permanently to Internet with a static IP address.

Thus a nameserver can not work on a temporary connectuin and/or a dynamic IP address, which is the case for standard phone or ADSL connections.

Since it is difficult for an individual to provide these servicers, some entities do offer to be your nameserver (see below ``Who provides DNS?'')

What is a secondary DNS?

(Summary)

Each domain name must be handled at least by two distinct nameservers, to enables fail over in case one of the two does not work correctly.

The two (or more) nameservers are exactly the same as seen from the Internet and have the same information on the domain name. On average all requests are at all time shared by all nameservers.

However when a modification is necessary (for example to change the IP address of a website), it is done only on one of them: the one configured as primary. All others, called secondary, will automatically update themselves, without any human intervention.

Who provides DNS?

(Summary)

Warning:
Your ISP gave you DNS information during your setup. Those DNS do not handle your domain name. You should not use them when you register a domain name.
In doubt, ask your provider for details.

DNS that you can use for your domain name are those provided by:

Gandi (without extra cost), (cf ``How to choose DNS?'')
your website hosting company, (cf ``DNS of your webhosting company'')
all entity having a permanent connection, and a computer configured as a nameserver (see ``Personnal DNS'')

Advantages of having a DNS with Gandi

(Summary)

Use of Gandi DNS, as well as associated services, is free of charge. You only pay the registration fee (see our Prices section).

Gandi offers you:

Full DNS hosting (primary and secondary DNS): Gandi's servers are connected permanently to Internet and thus can act as nameservers for your domain name if you so wish (see ``How to choose your DNS'')
Secondary DNS only: if you already have your own primary nameserver, you can ask Gandi to handle the secondary nameserver for your domain names (see ``Secondary DNS (Gandi)'').

By using Gandi's DNS, you can have the following services:

Email and/or Web redirections:

      Gandi redirects HTTP requests (requests of browser to access
      the website on your domain name) to the website of your choice
      (see ``DNS redirections ``Gandi)'')

      you can have up to 5 addresses (and a catchall) on your domain name
      as whatyouwish @ yourdomainname redirected to email adresses
      of your choice (see ``DNS redirections ``Gandi)'')

A/CNAME/MX records (zone file handling): you can define and change your zone through our Web interface.

      you can create A records in your domain name to whatever
      IP address you wish
      (see ``Custom DNS (Gandi)'')

      you can create aliases and subdomains in your domain name
      (see ``Custom DNS (Gandi)'')

      you can have servers handling mails in your domain name
      (see ``Custom DNS (Gandi)'')

Drawbacks of having a DNS at Gandi

(Summary)

Web redirection: when someone hits your website, he will see the real address of your website (at your hosting company) appearing in the browser navigation tab.
Email redirections: emails sent are limited to 2MB.
Zone handling: you can not modify/create SOA or NS records

How to choose your DNS

(Summary)

Use of Gandi servers is at no extra cost.

WARNING ON DELAYS:

Every DNS modification has consequences on your domain name availability. It is taken into account immediately in Gandi's database, but you need to wait few days so that it is seen on all Internet servers (propagation delays). These delays do not depend on Gandi.

6 choices:

You do not have them : see ``DNS parking (Gandi)''
You would like to use our redirection services : see ``DNS redirection (Gandi)''
You know how to configure a zone : see ``Custom DNS (Gandi)''
Your webhosting company gave to you its DNS : see ``DNS of your webhosting company''
You have your own nameservers : see ``Personnal DNS''
You have your own primary nameserver, and would like Gandi to be your secondary: cf ``Secondary DNS (Gandi)''

DNS parking (Gandi)

(Summary)

You do not have nameservers for your domain name (your website is not ready yet, or you do not have already a webhosting company): Gandi DNS are available for you.

During registration,

with the simplified interface, domain names registered are automatically using Gandi DNS (you will also have the opportunity further in the registration to choose your redirections)
with the complete interface, you just need to use button ``Primary Gandi'' to use Gandi DNS nameservers

If you so wish, you will be able later to stop the redirection when the domain name will be registered (see ``Stop Gandi redirection'')

As soon as you have a webhosting company, you will just need to replace the current (Gandi) DNS by those given to you by your webhosting company (see ``DNS of your webhosting company)

DNS redirection (Gandi)

(Summary)

With Gandi's DNS you can have at any time our web and/or email redirection services, even if you were using DNS of your webhosting company.

During registration of the domain name : see previous question
For an existing domain names (already handled by Gandi): you can, at any time, choose to use, modify or delete (see ``Stop Gandi redirection'') your redirctions, by using link ``Change your GANDI hosting choices'' in our Administration section.

Names and IP adresses of our DNS will be automatically added to your domain name.

Stop Gandi redirection

(Summary)

If you want to still use Gandi DNS but not having any redirections anymore, you just need to use link ``Change your GANDI hosting choices'' in the Administration section, to delete all redirections and validate.

If you want to use other nameservers, you will need to use link ``Change your DNS hosting from GANDI to another service'' of the Administration section (see ``DNS of your webhosting company'' for further details).

In this last case, so that your website remains available during the switch, our servers will maintain the redirection for few days, to leave time to the new servers to handle things (propagation delays). Those Gandi redirections will not interfere with the success of this change, and will ensure lack of service interruption.

If you want to use our custom DNS service instead of our redirections service, please see below ``Custom DNS (Gandi)''.

Custom DNS (Gandi)

(Summary)

You know how to configure A, MX, or CNAME records in a Bind zone file : you can use our custom DNS service.
For that, you just need to use link ``Customized DNS'' in our Administration section.

You will be able there to define and modify the content of your zone. Modifications will be applied on Gandi DNS every 15 minutes.

Please note carefully that this service is incompatible with our redirection service.

WARNING:
This service is restricted to advanced users. The subject being far too vast, we will not be able to provide support on the use of this service. In particular please make sure not to create, for the same ressource, a CNAME record and an A or MX record, since then your whole zone will be rejected, and your domain name will disappear from the DNS. This configuration is invalid.

DNS of your webhosting company

(Summary)

You just hosted your website, or changed your webhosting company. You need to update your DNS for your domain name.

If you are currently using our redirections service or our custom DNs service : you need to use in the Administration section link ``Change your DNS hosting from GANDI to another service''

     There, you will need to provide the following information
     given by your webhosting company:
     - names and IP adresses of nameservers to be used
     - GANDI ID of your webhosting company, which will become
     technical contact.

     Only your webhosting company has all this information.
     If needed, please contact them.

If you are currently using other nameservers, you will need to follow link ``Modify some of your domain name parameters'' in our Administration section.

     There, you will be able to change nameservers (if you are technical
     or administrative contact of the domain name concerned), and
     also if necessary to change the technical contact (if you are the
     administrative contact).

After the change is made, Gandi will not provide any more any kind of redirections. For all problems on this subject, you will need to get in touch directly with your webhosting company.

Personnal DNS

(Summary)

You have a permanent link, and you have configured your own DNS. You need to update your DNS for your domain name.

First, verify that your nameservers are correctly registered with the concerned Registry.

      To register a new nameserver, please contact the owber of the domain
      name in which the name of the nameserver is.

      If this domain name is handled currently by Gandi, its administrative
      contact will be able to register your nameserver through our Administration
      section, link ``Create, modify or delete a nameserver''

To make the DNS change, please see previous question. You can use your own GANDI ID as the new technical contact.

WARNING:
Except when using our secondary DNS (see below), your new list of DNS should not have any nameservers of Gandi: they will not be configured correctly for your domain name, and thus it will not work correctly.

Secondary DNS (Gandi)

(Summary)

You have your own primary nameserver, but you need a secondary and wish Gandi to provide this service to you.

Through our Administration section and link ``Modify some of your domain name parameters'', you just need to add at the second position (or further below) this nameserver: ns6.gandi.net (IP address is not needed)

Our DNS server will be automatically configured after your validation. It will be active for your domain name at most 24 hours after your modification. It will synchronize itself periodically on the first nameserver of the list.

URL of this document : http://www.gandi.net/faq/dns.html