The US Department of Defense has 42 million billion billion billion IPv6 addresses

Just as it did with IPv4, the US Department of Defense has managed to get its hands on a huge chunk of the addresses of its successor, IPv6.

The US DoD has a /13 IPv6 block (the smaller the number, the larger the block). No one else in the world is even close to that. The next-largest block after that is a /19 block (which is already huge). In other words the DoD owns a block 64 times larger than anyone else’s.

But just wait until you see how many IP addresses that really is. (Ok, the headline kind of gives it away, but we’ll expand on that.)

So, how many IP addresses is that?

A /13 block contains 2^115 IPv6 addresses. That is 42 million billion billion billion addresses, or put another way: 42 followed by 33 zeros.


We had to look up what a number that large is actually called: 42 decillion. That was a new one for us…

Further perspective on how large the US DoD IP block is

It can be hard to properly picture such a large number, so here are a few examples to give you some perspective. (Hint, 42 decillion is a positively ginormous number.)

  • If you stacked that many US dollar coins on top of each other, the stack would be 84 billion billion billion km high (52 billion billion billion miles).
  • The height of that stack of dollar coins would be 88 billion times the diameter of the Milky Way.
  • If the US DoD added one new device every second and each got its own IP address, they wouldn’t run out until 1.3 billion billion billion years from now.

We recalculated these numbers three times. They simply seemed too insanely large at first.

Looks like the DoD won’t have a shortage of IP addresses anytime soon… And you can add to this that they already own a huge chunk of the IPv4 address space.

Who owns the largest IPv6 blocks?

For the curious, here is a list of the largest IPv6 blocks on the Internet today and who owns them:

The largest IPv6 blocks on the Internet
Owner Block size Number of IP addresses
United States Department of Defense (DoD) /13 4.2E+34
France Telecom /19 6.5E+32
Deutsche Telecom /19 6.5E+32
Korea Telecom /20 3.2E+32
SoftbankBB IPv6 Network /20 3.2E+32
Australian Government Department of Defense /20 3.2E+32
InterBusiness /20 3.2E+32
TeliaSonera /20 3.2E+32
Telstra Internet /20 3.2E+32
Cable & Wireless Telecommunication Services /21 1.6E+32
Nippon Telegraph and Telephone West Corporation /21 1.6E+32
HiNet Taiwant /21 1.6E+32
Polish Telecom /21 1.6E+32

Source for IPv6 prefix data: SixXS

Other recent IPv6 articles: A crisis in the making: Only 4% of the Internet supports IPv6s


  1. While the DoD does have a large(!) allocation, any IPv6 conversation should be framed around the number of networks (/64s) available – not the number of individual hosts/addresses.


  2. The number of unique identifier is not accurate. You need to take into account that each interface in IPv6 word is /64. In addition to that if the DoD already has a bunch of IPv4 space that they really use … and if they are in the process of replacing IPv4 by IPv6 … then it may make sense for them to request bunch of IPv6! All in all I guess they have provided sufficient justifications to ARIN folk … Now other government agencies around the world that need IPv6 addresses should also follow the DoD and request their part NOW … doing so, tomorrow we won’t be talking about unbalanced allocation … React instead of complain!


  3. @dexter

    We REALLY don’t need to worry about unbalanced allocation. There are just so many IPv6 addresses that we’ll run out of just about everything else before we run out of addresses. It’s really past the point of needing to be worried about.

  4. Okay.. I can understand the US DoD and also the French and German telcos (~64 million people), but WTF are the Australian Government Department of Defense up to?

  5. Actually it makes total and complete sense for the DOD to grab that many IP’s even the Australian DOD.

    IF it was me though I would have a Joint Federal Agency that obtained a block that size or evne a littel larger for EVERY government agency, ANONYMITY is the game the DoD is playing here.

    Think about folks the weakest link in the DoD system or any other for that matter is whether I can FIND you or not. Right now with the current IPv4 it is rather fairly easy to find any government servers and even for that matter a persons actual IP address. It takes trial and error and even network scanning but basically with the current IPv4 system it is possible ot map out an entire ISP, or city, or even sometimes a neighborhood.

    So think about it for a minute, at 1 item per second they wouldn’t run out until 1.3 billion billion billion years from now. So hwo LONG do you think it would take HACKERS to find the RIGHT computer in the haystack now? If they scanned all the ips and did 3 per second would still be 1 Billion years to map all the IPS, but then again your map would be wrong! Who says the DOD is not going ot utilize some form of dynamic IP setting for their new network?

    Depending on the agency and the sensitivity of any area they change passwords on a daily or weekly bases what’s to say they cannot change Critical server IP’s on a weekly basis as well?

    I for think this is a BRILLIANT move for any “security” agency to do. I just think they could have made it fdar more secure and anonymous by simply having 1 Federal agency in each Country obtain IP’s for ALL on their respective federal agencies in the country and then assign them as needed, only have IANA records solely for the public webservers.

    But I doubt that would happen cause most agencies do nto play well together as we have witnessed over the many years:)

    I any event whoever made this decision made a Brilliant one!

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