An IP (Internet Protocol) address is a numerical name that is assigned to a machine so that other machines can find it and communicate with it over the internet.
IP addresses are unique, meaning that there is only one per machine (or virtual machine, as in the case of a Gandi virtual server).
Just like domain names, each IP address is registered to a person or organization. You can perform a whois lookup of an IP Address to see information about it. For example, here is a whois look-up of 217.70.177.39:
inetnum: 217.70.176.0 - 217.70.183.255 netname: GANDI-NET1 descr: GANDI SERVERS country: FR admin-c: NG183-RIPE tech-c: NG183-RIPE notify: noc@gandi.net mnt-by: GANDI-NOC changed: mik+ripe@gandi.net 20070817 source: RIPE status: ASSIGNED PA role: NOC Gandi address: GANDI address: 15 place de la Nation address: 75011 Paris e-mail: noc@gandi.net admin-c: FLD-RIPE tech-c: FLD-RIPE nic-hdl: NG183-RIPE mnt-by: GANDI-NOC remarks: ------------------------------------------------- remarks: GANDI is an ICANN accredited registrar remarks: for more information: remarks: Web: http://www.gandi.net remarks: ------------------------------------------------- remarks: - network troubles: noc@gandi.net remarks: - SPAM complaints: abuse@gandi.net remarks: ------------------------------------------------- source: RIPE changed: fld@gandi.net 20070906 % Information related to '217.70.176.0/20AS29169' route: 217.70.176.0/20 descr: GANDI is an ICANN accredited registrar descr: for more information: descr: Web: http://www.gandi.net origin: AS29169 notify: noc@gandi.net mnt-by: GANDI-NOC changed: lfrigault@gandi.net 20030731 source: RIPE
This information allows you to see who is responsible for the machine, and where you can send abuse complaints or find other useful information about the IP address.
There are two types of IP addresses, version 4 (IPv4) and version 6 (IPv6). IPv6 addresses still make up a relatively small percentage of internet addresses.
Example of a version 4 IP address:
217.70.184.1
Example of a version 6 IP address:
fe80::222:15ff:fed7:d0dd
Here are just two of many examples of IP addresses in action.
In order for your your DNS (nameservers) to work, they need to be registered at the registry so that the host name is associated with an actual machine. This is done by creating a glue record for your name server.
When looking up a domain name in the whois database, these glue records appear as such:
nserver: dns0.gandi.net 217.70.177.39 nserver: dns1.gandi.net 217.70.177.45 nserver: dns2.gandi.net 217.70.177.46 nserver: dns3.gandi.net 217.70.179.36
So, for example, the IP address of the nameserver dns0.gandi.net is 217.70.177.39. This means that the actual machine where the DNS server is physically located is called 217.70.177.39.
So that your website can be visible on the web, your DNS need to know where to point the domain name. This is done by creating a record in your DNS zone file that indicates something to the effect of “if you get a request for X domain, then point the user to X server.”
In BIND syntax, this is done using A records. It looks like this:
@ 10800 IN A 217.70.184.34
Thus, in the above example, the IP address of the server where the website is physically hosted is called 217.70.184.34.