The Iranian government forces all ISPs in the country to singlehomed to and be downstream of DCI, the government run ASN. If you don't do this, you don't get an international transit connection, and men with guns come to take your routers and arrest you .
If Iran goes offline, all the connections that would have routed through it now route around it, so the internet is resilient. i.e. it's resilient for all of Iran's neighbors who will be unaffected.
The network was designed to be resilient and continue existing even if the individual nodes are brittle. Iran taking their nodes offline doesn't destroy the entire internet.
So it's possible to eclipse part of the network.
That was the point (in the DARPA context of this thread) -- nuke takes out a city, network still functions and routes around it. So signals are still getting from SAC to DC or whatever.
I guess our lesson here is to invest in mesh networking and services that work over it, before it's too late.
>making a resilient, attack-resistant network
I'm curious how you can be resistant against a entity with a monopoly on violence.
Not that DARPA failed. New countermeasures will always emerge, you cant predict the future.