What I was saying is the "standard" (ISO 3166) seems reasonably made for "one planet, one network" (even if a little USA-centric, but it's understandable as they deployed the first nodes and 're still hosting the TLD backbone hosts).

In the space era, I believe, we should start thinking of networks which may go beyond a single planet (maybe leaving for the future to go beyond a single solar system ;-)).
That's why a .space TLD is "acceptable" today, in the lack of a wider TLD's concept/hierarchy. As "TLD" is thought as TOP-Level-Domain but, having "something" out of Earth's contro, there will be something "over" a TLD where to route messages (that's why I wrote about "routing", in kind of non-technical way).
.XA may start going in the "space era" direction but, as far as I can see, nearly in the same way .space goes, just seeming "more nation's related" with some little additional benefit (btw: the exactly same reason why GB asked for (and obtained) .UK).

I've some difficult to figure a future asgardia.gov.space domain, as it relies to some kind of ".gov.space" which won't be us (maybe, better, gov.asgardia.space at this point, with subdomains like ministryoffinance.gov.asgardia.space).
Using an .XA TLD, instead, will give us the whole control/responsability over our TLD (and, if we'll be a Nation, we'll should have it). So we'll may have www.asgardia.xa as our "main page", ministryoffinance.gov.xa (as "XA" will represent "Asgardia" by itself) and so on... am I right? (I'm just thinking about it, not claiming I'm right for sure)

To be honest, the TLD hierarchy should be amended to take in count "extraTerrestrial" domains. So, all our actual TLDs should end into .earth or .sol3. ;-)

But then analyse the gain from all that hoop jumping.

.earth sounds a little vague to me - and about as much practical use as .internet at least until there's something with operations on more than one planet.

As to how many "space nations" - I'd not expect many to form for quite some time, but once long term mass habitation of space becomes an actual thing then one must expect others to also appear, and various subsections to possibly fracture from us. Maybe as a species it would of been learned to better observe similarities and lesser observe lines drawn on a map and could stand a chance at forming a single nation, species wide - but that's a little much to hope for IMHO.

Absolutely agree that it's a little early (lol) to think in terms of "the Galaxy(es)" and even about more than one solar system... but we're not that far to establish a Moon colony (we can do it, even if we're not actively doing it, AFAIK), the same as a colony on Mars: that's why I thought about a "(local) solar system extension" to the actual TLD structure. ;-)
I'm sure, at the beginning, every new "entity" will be treated as a particular case of the more general Earth organization (TLD, as we was speaking about that), so with some kind of Xn/Xnn extension (thus the .XA).

I was just speculating about having a couple of wide colonies onto Mars, as well as another on the Moon, as well as some other colonies spreaded in the space (e.g. at Lagrange points or near to the asteroids' belt), all of them (and one of them will be our one ;-)) being an independent Nation, independent from the Earth also, so why using the same "Earth's TLD structure" and not a different subset from a new, solar system wide, superset?

@petrv
Something like that, yes.
asgardia.xa.sol, as a (possibly) "mobile solar system colony" but, in an Earth-centric (transitional) model, even asgardia.xa is ok, for now. ;-)

Is the current DNS structure likely to exhaust all possible combinations?

I don't see the sense in attempting to refactor it.

I have been doing some research and provided asgardians are willing to switch to using an OpenNIC DNS server, there may be hope. new-nations.net.

This may be able to hold over with a *.asg domain until we can obtain a "standard" DNS domain.

On the topic of a TLC (which I think something short like .asg, would be best), how about the problems with Internet connectivity in space? We may need better or revised routing protocols to handle what would likely be slow or interment links.

Some things I found: 1) NASA experiments on space communications: https://www.nasa.gov/mission_pages/station/research/experiments/730.html; 2) NASA's first steps for high speed Internet connectivity in space: https://www.nasa.gov/feature/goddard/2017/nasa-taking-first-steps-toward-high-speed-space-internet; 3) Wikipedia page on Interplanetary Internet: https://en.wikipedia.org/wiki/Interplanetary_Internet

I really like the .asg domain idea.