: IP history of a No-IP host I use No-IP so that hello.ddns.net points to a server that has a dynamic IP. Is it possible to see the history of IPs a No-IP host took?

@Jamie184

This answer may be overly simplistic. I apologize if that is the case. I am think of all of those who may stumble across this page.

NoIP is a DDNS (dynamic domain name service). Every domain name must have an IP address in order for the network to know how to address packets and route them through the Internet and indeed any TCP/IP based network. How a DDNS system works is that a computer must report it's current IP address to the DDNS using software along with the domain name. From there, the DDNS hosts the domain name and links it to an IP address dynamically meaning that a user does not have to specifically identify an IP address with a host name in the traditional way but does so in an automatic and convenient way. This is an important feature for some who need to participate in the Internet in a larger way than a casual user but does not have a static IP address assigned to them. Most users of the Internet are subscribers to a service which uses dynamically assigned IP addresses taken from a pool of addresses. These can change every time a user accesses the Internet or in the case of DSL where the access is for a longer period of time, when the user connects and the address lease expires.

That said, it is possible to resolve any domain name be tied to an IP address at any given point, however, this requires resolving the domain name which is a specific action normally taken in the background as the user accesses the network. There are services that keep track of domain name and IP address assignments, however, because of the scale of the Internet, this is not done an a granular way. This means that a user can connect several times a day and have several different IP addresses assigned to a domain name, but because the services that track these things cannot realistically track all of these accesses, many will go unnoticed. One of the reasons for this is because DDNS is not the large market it was years ago with broadband now so prevalent and the need to track these domain names is simply not there.

Part of the problem is that most DDNS services do not set PTR (reverse) records which means that a domain name can resolve to an IP address, but the same IP address will not likely resolve back to the domain name. This means that the domain name must be known in order to track it. With a PTR record, this is not necessary. It is far simpler to reverse look-up IP addresses since they are well defined and known. More specifically, it is possible to know what IP addresses are subscriber IP addresses and in particular which pools of IP addresses belong to a DDNS service.

So to answer your question, it is possible to get some of the IP addresses of a domain name that uses DDNS, but not likely all of them. Most whois websites can give you this information if they are aware of the domain name. But again, it is not very granular.

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