If two hosts X
and Y
are connected to the Internet with NAT.
Both NATs are of cone-restricted type.
Now assume there's a server Z
which stores all translated public addresses of X
and Y
.
Both X
and Y
can get each other's translated public IP address from Z
.
Now X
wants to talk to Y
, but X
can't send a message to Y
using Y
's public IP because Y
's NAT is cone-restricted.
But if both X
and Y
send a message to each other simultaneously, then their message can reach X
and Y
.
Can anyone tell me why this happens??