I run some Internet services on my home Internet connection, mostly for myself but also for friends and family. The IPv4 address assigned to my home by my ISP (currently: BT Internet) is dynamic and changes from time to time. To get around this, I make use of a "dynamic dns" service: essentially, a web service that updates a hostname whenever my IP changes.

Since sometime last year I have also had an IPv6 address for my home connection: In fact, lots of them. There are more IPv6 addresses assigned to my home than there are IPv4 addresses on the entire Internet: 4,722,366,482,869,645,213,696 compared to 4,294,967,296 IPv4 addresses for the entire world (of which 3,706,452,992 are usable).

I am relatively new to IPv6 (despite having played with it on and off since around the year 2000). I was curious to find out how stable the IPv6 addresses are, compared to the IPv4 one. It turns out that it's very stable: I've had four IPv4 addresses since February this year, but my IPv6 allocation has not changed.


comment 1
... and probably never will. I don't know about BT Internet, but most providers provding v6 to private customers just assign them a fixed /64.
Comment by steinex
comment 1
Okay, but does your dyndns do IPv6?
Comment by Derek
comment 4

there are privacy extensions that many recommend turning on, and they make sense for outgoing-only hosts. Essentially, the latter half of the address is randomised.

The German so-called "IPv6 council" has issued the recommendation in 2012 to ISPs to also randomise the prefix (the former half), similar to dynIPv4. The reasoning is that a static prefix already allows the identification of a customer, rendering the privacy extensions pointless. https://web.archive.org/web/20121207001716/http://www.ipv6council.de/documents/leitlinien_ipv6_und_datenschutz.html

I don't know whether this "recommendation" exists elsewhere, and I do see the point — except of course who cares about IP source addresses in the days of browser fingerprinting and even more sophisticed identification/tracking techniques. However, it's of course a nightmare for those of us who need a stable IPv6 to be able to reach nodes within our respective networks.

Comment by Martin Krafft
comment 3

Okay, but does your dyndns do IPv6?

Actually, no: I'm using namecheap's dyndns service with a custom domain and it does not support IPv6. However, I'm evaluating https://dynv6.com who do.