-: In the last lesson, we discussed the concept of
a denial of service attack,
and we went over all of the different types of them,
but most modern systems can't be taken down
by a single machine attempting a denial of service anymore,
so attackers got smarter and they created
a distributed denial of service, or DDoS.
Now, a distributed denial of service attack,
instead of using a single attack targeting one server,
they use hundreds or even thousands of machines
to launch an attack simultaneously against a single server,
and force it offline to create
that denial of service condition.
Usually, these machines that conduct the attack
don't even realize that they're a part of it, though.
Generally, these machines have become zombies or bots
inside a large botnet and then when they receive
that command to attack,
they all simultaneously send all their payloads
against a single victim.
Now, in addition to most basic forms of DDoS attacks,
there is one specific type of DDoS attack called
a DNS amplification attack that could be performed.
This specialized DDoS allows an attacker to generate
a high volume of packets that's intended to flood
a victim's website by initiating DNS requests from
a spoof version of the target's IP address.
This causes the DNS servers to respond to that request
and send the response back to the server,
thinking that it's valid.
Because a DNS request uses very little bandwidth to send,
but the response usually takes up a lot more bandwidth,
this allows the attack to be amplified against
the victim's server.
Also, if this is happening because thousands
of simultaneous requests are being made
by a bunch of zombies and a botnet
on behalf of your victim's server,
you can easily become overwhelmed with a lot of information
and eat up lots of bandwidth pretty quickly,
causing that denial of service condition to occur.