If you run the traceroute command (tracert in Windows I think) you can see all the places where your traffic went
This is the trace from somewhere to communities.win (I have taken out the first two for anonomysing purposes)
3 nott-core-2b-xe-1112-0.network.virginmedia.net (80.1.79.241) 6.102 ms 4.046 ms 6.058 ms
4 * * *
5 m674-mp2.cvx1-b.lis.dial.ntli.net (62.254.42.162) 13.050 ms 10.968 ms 13.083 ms
6 ix-ae-30-0.tcore1.ad1-amsterdam.as6453.net (80.231.80.30) 10.338 ms 10.728 ms 9.330 ms
7 if-ae-7-3.tcore1.av2-amsterdam.as6453.net (80.231.80.57) 9.994 ms if-ae-2-33.tcore1.av2-amsterdam.as6453.net (195.219.150.114) 9.991 ms if-ae-7-3.tcore1.av2-amsterdam.as6453.net (80.231.80.57) 9.543 ms
8 195.219.194.94 (195.219.194.94) 11.139 ms 11.139 ms 11.096 ms
9 172.67.213.135 (172.67.213.135) 9.631 ms 9.502 ms 19.449 ms
The Amsterdam exchange is another core exchange.
While you have heard "the Internet routes around damage" there are key points along any route and with enough damage the remaining routes get flooded with too much traffic and things grind to a halt.
Apart from physical control, the DNS system relies on 13 root servers
Then there are the routing tables aka BGP. It has long been speculated that determined attackers could cause significant harm if they managed to inject BGP routing data into the ecosystem
As you might imagine, the state has their own separate cable network disconnected from the Internet too. Or at least I know about the UK's Police Network as I used to do a bit of IT support in a local police station, I presume it is still the same. Some police have two computers on their desk, one connected to each system.
Private networks also exist, both commercial and hobby.
FidoNet, for instance, is an independent network of volunteers providing non-Internet based communications
There are three cables providing Internet access to Cuba
GTMO-PR - which attaches Guantanamo Bay to Pueto Rico
GTMO-1 - which attaches Guantanamo Bay to Florida
As the name suggests these are operated by the US Govt.
Whether any public traffic ever went over those cables, I don't know.
and
ALBA-1 which goes from Jamaica to Cuba, and from Cuba to Venezuela
and is 60% owned by state-run CVG Telecom (now Telecom Venezuela) and 40% by Cuban Transbit.
So to "black out" Cuba, simply block access to that route.
The term can also be used by a VPN. A kill switch on a VPN prevents internet access when the VPN is disconnected. It prevents leaks should a site send a request while you are not connected through the VPN.
The internet relies on peering and this happens in specific places.
For instance, see this underwater cable map, there are approx 420 undersea cables connecting the countries together.
https://www.submarinecablemap.com/
On land there are places dedicated to being data exchanges
e.g. https://www.linx.net/
in London
If you run the traceroute command (tracert in Windows I think) you can see all the places where your traffic went
This is the trace from somewhere to communities.win (I have taken out the first two for anonomysing purposes)
3 nott-core-2b-xe-1112-0.network.virginmedia.net (80.1.79.241) 6.102 ms 4.046 ms 6.058 ms
4 * * *
5 m674-mp2.cvx1-b.lis.dial.ntli.net (62.254.42.162) 13.050 ms 10.968 ms 13.083 ms
6 ix-ae-30-0.tcore1.ad1-amsterdam.as6453.net (80.231.80.30) 10.338 ms 10.728 ms 9.330 ms
7 if-ae-7-3.tcore1.av2-amsterdam.as6453.net (80.231.80.57) 9.994 ms if-ae-2-33.tcore1.av2-amsterdam.as6453.net (195.219.150.114) 9.991 ms if-ae-7-3.tcore1.av2-amsterdam.as6453.net (80.231.80.57) 9.543 ms
8 195.219.194.94 (195.219.194.94) 11.139 ms 11.139 ms 11.096 ms
9 172.67.213.135 (172.67.213.135) 9.631 ms 9.502 ms 19.449 ms
The Amsterdam exchange is another core exchange.
While you have heard "the Internet routes around damage" there are key points along any route and with enough damage the remaining routes get flooded with too much traffic and things grind to a halt.
Apart from physical control, the DNS system relies on 13 root servers
https://securitytrails.com/blog/dns-root-servers
take those out and everything grinds to a halt
Then there are the routing tables aka BGP. It has long been speculated that determined attackers could cause significant harm if they managed to inject BGP routing data into the ecosystem
https://www.ccsinsight.com/blog/the-internet-takedown/
So, to be clear, as you seem pretty knowledgeable about this all, you think that a total black-out is more probable than not, right?
It's an interesting question people have pondered all along.
It would probably take Co-ordination of Nations to black out the whole thing.
That seems the least likely outcome.
More like blocks of countries would be disconnected from each other but their internal networks keep functioning.
Russia recently tested a total disconnect from the Global Internet to test their resilience from that attack vector.
https://www.nationalsecurity.news/2021-07-28-russia-successfully-disconnects-itself-from-global-internet.html
As you might imagine, the state has their own separate cable network disconnected from the Internet too. Or at least I know about the UK's Police Network as I used to do a bit of IT support in a local police station, I presume it is still the same. Some police have two computers on their desk, one connected to each system.
Private networks also exist, both commercial and hobby.
FidoNet, for instance, is an independent network of volunteers providing non-Internet based communications
https://www.fidonet.org/
So, it depends on who is doing the blacking out and why.
It would be really rough. Everything is plugged in, supply lines included and what job doesn't somehow utilize the internet? Shit would get dark.
as of today, all of cuba does not have internet.
To use my post from above to demonstrate
https://www.submarinecablemap.com/
There are three cables providing Internet access to Cuba
GTMO-PR - which attaches Guantanamo Bay to Pueto Rico
GTMO-1 - which attaches Guantanamo Bay to Florida
As the name suggests these are operated by the US Govt.
Whether any public traffic ever went over those cables, I don't know.
and
ALBA-1 which goes from Jamaica to Cuba, and from Cuba to Venezuela
and is 60% owned by state-run CVG Telecom (now Telecom Venezuela) and 40% by Cuban Transbit.
So to "black out" Cuba, simply block access to that route.
The term can also be used by a VPN. A kill switch on a VPN prevents internet access when the VPN is disconnected. It prevents leaks should a site send a request while you are not connected through the VPN.