This article will give you a short introduction to DDNS, and will only apply to a precise example. I will not detail the reasons of my choice. However, the links provided at the end of the document will allow you further understand the uses that can be made of DDNS.
2 machines running GNU/Linux: one at home with a dynamic IP, the other elsewhere with a fix IP
BIND 9.2.0 or newer should be installed on the external machine (and act as primary DNS for your domain – the setup won’t be detailed here)
the nsupdate utility on your router at home. This comes as part of the dnsutils Debian package.