[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.90,0:00:04.50,Default,,0000,0000,0000,,(upbeat piano and drum music)
Dialogue: 0,0:00:10.02,0:00:11.55,Default,,0000,0000,0000,,- Hi. My name is Paola,
Dialogue: 0,0:00:11.55,0:00:14.50,Default,,0000,0000,0000,,and I am a software engineer at Microsoft.
Dialogue: 0,0:00:14.50,0:00:17.08,Default,,0000,0000,0000,,Let's talk about how the internet works.
Dialogue: 0,0:00:17.08,0:00:19.93,Default,,0000,0000,0000,,My job relies on networks being able
Dialogue: 0,0:00:19.93,0:00:21.93,Default,,0000,0000,0000,,to talk with one another.
Dialogue: 0,0:00:21.93,0:00:24.77,Default,,0000,0000,0000,,But back in the 1970s, there was no
Dialogue: 0,0:00:24.77,0:00:26.96,Default,,0000,0000,0000,,standard method for this.
Dialogue: 0,0:00:26.96,0:00:29.82,Default,,0000,0000,0000,,It took the work of Vint Cerf and Bob Kahn
Dialogue: 0,0:00:29.82,0:00:32.13,Default,,0000,0000,0000,,to invent the Internetworking Protocol
Dialogue: 0,0:00:32.13,0:00:34.31,Default,,0000,0000,0000,,to make communication possible.
Dialogue: 0,0:00:34.64,0:00:36.57,Default,,0000,0000,0000,,This invention laid the groundwork
Dialogue: 0,0:00:36.57,0:00:38.98,Default,,0000,0000,0000,,for what we now call the internet.
Dialogue: 0,0:00:39.57,0:00:42.04,Default,,0000,0000,0000,,- The internet is a network of networks.
Dialogue: 0,0:00:42.04,0:00:45.50,Default,,0000,0000,0000,,It links billions of devices\Ntogether all around the globe.
Dialogue: 0,0:00:46.72,0:00:48.71,Default,,0000,0000,0000,,Maybe you're connected with a laptop
Dialogue: 0,0:00:48.71,0:00:50.90,Default,,0000,0000,0000,,or a phone through wifi.
Dialogue: 0,0:00:50.90,0:00:52.52,Default,,0000,0000,0000,,But then that wifi connection
Dialogue: 0,0:00:52.52,0:00:55.72,Default,,0000,0000,0000,,connects to an Internet\NService Provider, or ISP.
Dialogue: 0,0:00:55.72,0:00:58.36,Default,,0000,0000,0000,,And that ISP connects you\Nto billions and billions
Dialogue: 0,0:00:58.36,0:01:00.20,Default,,0000,0000,0000,,of devices around the world
Dialogue: 0,0:01:00.20,0:01:02.12,Default,,0000,0000,0000,,through hundreds of thousands of networks
Dialogue: 0,0:01:02.12,0:01:04.04,Default,,0000,0000,0000,,that are all interconnected.
Dialogue: 0,0:01:05.46,0:01:08.68,Default,,0000,0000,0000,,One thing that most\Npeople do not appreciate,
Dialogue: 0,0:01:08.68,0:01:12.14,Default,,0000,0000,0000,,is that the internet is\Nreally a design philosophy
Dialogue: 0,0:01:12.14,0:01:16.11,Default,,0000,0000,0000,,and an architecture expressed\Nin a set of protocols.
Dialogue: 0,0:01:16.60,0:01:19.63,Default,,0000,0000,0000,,A protocol is a well-known set\Nof rules and standards that,
Dialogue: 0,0:01:19.63,0:01:21.42,Default,,0000,0000,0000,,if all parties agree to use it,
Dialogue: 0,0:01:21.42,0:01:23.78,Default,,0000,0000,0000,,will allow them to\Ncommunicate without trouble.
Dialogue: 0,0:01:24.93,0:01:28.80,Default,,0000,0000,0000,,How the internet actually\Nphysically works is less important
Dialogue: 0,0:01:28.80,0:01:31.76,Default,,0000,0000,0000,,than the fact that this\Ndesign philosophy has allowed
Dialogue: 0,0:01:31.76,0:01:33.92,Default,,0000,0000,0000,,the internet to adapt and absorb
Dialogue: 0,0:01:33.92,0:01:36.24,Default,,0000,0000,0000,,new communication technologies.
Dialogue: 0,0:01:36.24,0:01:38.46,Default,,0000,0000,0000,,This is because in order\Nfor a new technology
Dialogue: 0,0:01:38.46,0:01:40.65,Default,,0000,0000,0000,,to use the internet in some fashion,
Dialogue: 0,0:01:40.65,0:01:43.46,Default,,0000,0000,0000,,it just needs to know which\Nprotocols to work with.
Dialogue: 0,0:01:44.76,0:01:46.78,Default,,0000,0000,0000,,All the different devices on the internet
Dialogue: 0,0:01:46.78,0:01:48.49,Default,,0000,0000,0000,,have unique addresses.
Dialogue: 0,0:01:48.49,0:01:50.86,Default,,0000,0000,0000,,An address on the\Ninternet is just a number,
Dialogue: 0,0:01:50.86,0:01:54.08,Default,,0000,0000,0000,,similar to a phone number,\Nor a sort of street address
Dialogue: 0,0:01:54.08,0:01:56.25,Default,,0000,0000,0000,,that's unique to each computer or device
Dialogue: 0,0:01:56.25,0:01:57.68,Default,,0000,0000,0000,,at the edge of the network.
Dialogue: 0,0:01:59.31,0:02:01.76,Default,,0000,0000,0000,,This is similar to how most\Nhomes and businesses have
Dialogue: 0,0:02:01.76,0:02:03.10,Default,,0000,0000,0000,,a mailing address.
Dialogue: 0,0:02:03.10,0:02:04.50,Default,,0000,0000,0000,,You don't need to know a person
Dialogue: 0,0:02:04.50,0:02:05.83,Default,,0000,0000,0000,,to send them a letter in the mail,
Dialogue: 0,0:02:05.83,0:02:08.34,Default,,0000,0000,0000,,but you do need to know their address,
Dialogue: 0,0:02:08.34,0:02:10.14,Default,,0000,0000,0000,,and how to write the address properly,
Dialogue: 0,0:02:10.14,0:02:12.34,Default,,0000,0000,0000,,so the letter can be\Ncarried by the mail system
Dialogue: 0,0:02:12.34,0:02:13.89,Default,,0000,0000,0000,,to its destination.
Dialogue: 0,0:02:14.25,0:02:15.85,Default,,0000,0000,0000,,The addressing system for computers
Dialogue: 0,0:02:15.85,0:02:17.72,Default,,0000,0000,0000,,on the internet is similar,
Dialogue: 0,0:02:18.11,0:02:20.64,Default,,0000,0000,0000,,and it forms part of one\Nof the most important
Dialogue: 0,0:02:20.64,0:02:23.35,Default,,0000,0000,0000,,protocols used in internet communication,
Dialogue: 0,0:02:23.35,0:02:26.24,Default,,0000,0000,0000,,simply called the\NInternet Protocol, or IP.
Dialogue: 0,0:02:26.96,0:02:30.07,Default,,0000,0000,0000,,A computer's address, then,\Nis called its IP address.
Dialogue: 0,0:02:30.51,0:02:33.22,Default,,0000,0000,0000,,Visiting a website is really\Njust your computer asking
Dialogue: 0,0:02:33.22,0:02:35.30,Default,,0000,0000,0000,,another computer for information.
Dialogue: 0,0:02:35.30,0:02:37.63,Default,,0000,0000,0000,,Your computer sends a message\Nto the other computer's
Dialogue: 0,0:02:37.63,0:02:41.01,Default,,0000,0000,0000,,IP address, and it also sends\Nalong its origin address
Dialogue: 0,0:02:41.01,0:02:43.67,Default,,0000,0000,0000,,so the other computer knows\Nwhere to send its response.
Dialogue: 0,0:02:45.75,0:02:47.90,Default,,0000,0000,0000,,- You may have seen an IP address.
Dialogue: 0,0:02:47.90,0:02:49.74,Default,,0000,0000,0000,,It's just a bunch of numbers.
Dialogue: 0,0:02:50.04,0:02:52.80,Default,,0000,0000,0000,,These numbers are\Norganized in a hierarchy.
Dialogue: 0,0:02:53.42,0:02:55.68,Default,,0000,0000,0000,,Just like a home address has a country,
Dialogue: 0,0:02:55.68,0:02:58.64,Default,,0000,0000,0000,,a city, a street, and a house number,
Dialogue: 0,0:02:58.64,0:03:01.24,Default,,0000,0000,0000,,an IP address has many parts.
Dialogue: 0,0:03:01.47,0:03:03.25,Default,,0000,0000,0000,,Just like all digital data,
Dialogue: 0,0:03:03.25,0:03:06.25,Default,,0000,0000,0000,,each of these numbers\Nis represented in bits.
Dialogue: 0,0:03:06.66,0:03:09.98,Default,,0000,0000,0000,,Traditional IP addresses are 32 bits long,
Dialogue: 0,0:03:09.98,0:03:13.54,Default,,0000,0000,0000,,with eight bits for each\Npart of the address.
Dialogue: 0,0:03:13.54,0:03:15.95,Default,,0000,0000,0000,,The earlier numbers usually identify
Dialogue: 0,0:03:15.95,0:03:18.65,Default,,0000,0000,0000,,the country and regional\Nnetwork of the device.
Dialogue: 0,0:03:18.65,0:03:20.57,Default,,0000,0000,0000,,Then come the subnetworks.
Dialogue: 0,0:03:20.57,0:03:23.92,Default,,0000,0000,0000,,And then, finally, the address\Nof the specific device.
Dialogue: 0,0:03:24.44,0:03:28.48,Default,,0000,0000,0000,,This version of IP\Naddressing is called IPv4.
Dialogue: 0,0:03:28.48,0:03:30.97,Default,,0000,0000,0000,,It was designed in 1973,
Dialogue: 0,0:03:30.97,0:03:33.39,Default,,0000,0000,0000,,and widely adopted in the early '80s,
Dialogue: 0,0:03:33.39,0:03:36.73,Default,,0000,0000,0000,,and provides for more than\N4 billion unique addresses
Dialogue: 0,0:03:36.73,0:03:39.53,Default,,0000,0000,0000,,for devices connecting to the internet.
Dialogue: 0,0:03:39.80,0:03:43.17,Default,,0000,0000,0000,,But the internet has turned\Nout to be much more popular
Dialogue: 0,0:03:43.17,0:03:45.34,Default,,0000,0000,0000,,than even Vint Cerf imagined,
Dialogue: 0,0:03:45.34,0:03:48.68,Default,,0000,0000,0000,,and 4 billion unique\Naddresses won't be enough.
Dialogue: 0,0:03:48.68,0:03:51.46,Default,,0000,0000,0000,,We're now in the middle\Nof a multi-year transition
Dialogue: 0,0:03:51.46,0:03:55.79,Default,,0000,0000,0000,,to a longer IP address format called IPv6,
Dialogue: 0,0:03:55.79,0:03:59.54,Default,,0000,0000,0000,,which uses 128 bits per address,
Dialogue: 0,0:03:59.54,0:04:04.54,Default,,0000,0000,0000,,and provides over 340\Nundecillion unique addresses.
Dialogue: 0,0:04:05.13,0:04:08.01,Default,,0000,0000,0000,,That's more than enough for\Nevery grain of sand on Earth
Dialogue: 0,0:04:08.01,0:04:09.99,Default,,0000,0000,0000,,to have its own IP address.
Dialogue: 0,0:04:10.80,0:04:14.87,Default,,0000,0000,0000,,- Most users never see or\Ncare about internet addresses.
Dialogue: 0,0:04:14.87,0:04:18.16,Default,,0000,0000,0000,,A system called the Domain\NName System, or DNS,
Dialogue: 0,0:04:18.16,0:04:22.06,Default,,0000,0000,0000,,associates names, like www.example.com,
Dialogue: 0,0:04:22.06,0:04:24.05,Default,,0000,0000,0000,,with the corresponding addresses.
Dialogue: 0,0:04:24.05,0:04:27.18,Default,,0000,0000,0000,,Your computer uses the DNS\Nto look up domain names
Dialogue: 0,0:04:27.18,0:04:30.21,Default,,0000,0000,0000,,and get the associated\NIP address, which is used
Dialogue: 0,0:04:30.21,0:04:33.10,Default,,0000,0000,0000,,to connect your computer to the\Ndestination on the internet.
Dialogue: 0,0:04:33.10,0:04:34.100,Default,,0000,0000,0000,,- [Voiceover] And it goes a\Nlittle something like this.
Dialogue: 0,0:04:34.100,0:04:35.62,Default,,0000,0000,0000,,- Hey, hi there.
Dialogue: 0,0:04:35.62,0:04:39.45,Default,,0000,0000,0000,,I want to go to www.code.org
Dialogue: 0,0:04:41.31,0:04:45.01,Default,,0000,0000,0000,,- Yeah, well I don't know the\NIP address for that domain.
Dialogue: 0,0:04:45.01,0:04:46.73,Default,,0000,0000,0000,,Let me ask around.
Dialogue: 0,0:04:46.86,0:04:49.84,Default,,0000,0000,0000,,Hey, anyone know how to get to a...
Dialogue: 0,0:04:50.40,0:04:52.02,Default,,0000,0000,0000,,code.org?
Dialogue: 0,0:04:53.29,0:04:54.35,Default,,0000,0000,0000,,- Yeah, I got it right here.
Dialogue: 0,0:04:54.35,0:04:57.27,Default,,0000,0000,0000,,It's 174 dot 129
Dialogue: 0,0:04:57.27,0:05:00.18,Default,,0000,0000,0000,,dot 14 dot 120.
Dialogue: 0,0:05:00.51,0:05:01.84,Default,,0000,0000,0000,,- Oh, okay, great. Thanks.
Dialogue: 0,0:05:01.84,0:05:04.10,Default,,0000,0000,0000,,Yeah, I'm gonna write that\Ndown and save it for later
Dialogue: 0,0:05:04.10,0:05:05.08,Default,,0000,0000,0000,,in case I need it.
Dialogue: 0,0:05:05.08,0:05:06.76,Default,,0000,0000,0000,,Hey, here's that address you wanted.
Dialogue: 0,0:05:07.05,0:05:08.57,Default,,0000,0000,0000,,- Awesome. Thank you.
Dialogue: 0,0:05:10.53,0:05:13.79,Default,,0000,0000,0000,,(piano flourish)
Dialogue: 0,0:05:13.79,0:05:17.36,Default,,0000,0000,0000,,- So how do we design a\Nsystem for billions of devices
Dialogue: 0,0:05:17.36,0:05:21.11,Default,,0000,0000,0000,,to find any one of billions\Nof different websites?
Dialogue: 0,0:05:21.39,0:05:24.10,Default,,0000,0000,0000,,There is no way one DNS server
Dialogue: 0,0:05:24.10,0:05:27.41,Default,,0000,0000,0000,,can handle all of the\Nrequests from all devices.
Dialogue: 0,0:05:27.63,0:05:30.51,Default,,0000,0000,0000,,The answer is that DNS\Nservers are connected
Dialogue: 0,0:05:30.51,0:05:33.82,Default,,0000,0000,0000,,in a distributed hierarchy,\Nand are divided into zones,
Dialogue: 0,0:05:33.82,0:05:36.92,Default,,0000,0000,0000,,splitting up responsibility\Nfor the major domains
Dialogue: 0,0:05:36.92,0:05:40.90,Default,,0000,0000,0000,,such as .org, .com, .net, et cetera.
Dialogue: 0,0:05:41.83,0:05:44.13,Default,,0000,0000,0000,,DNS was originally created to be
Dialogue: 0,0:05:44.13,0:05:47.12,Default,,0000,0000,0000,,an open and public communication protocol
Dialogue: 0,0:05:47.12,0:05:49.87,Default,,0000,0000,0000,,for government and\Neducational institutions.
Dialogue: 0,0:05:49.87,0:05:51.59,Default,,0000,0000,0000,,Because of its openness,
Dialogue: 0,0:05:51.59,0:05:54.71,Default,,0000,0000,0000,,DNS is susceptible to cyber attacks.
Dialogue: 0,0:05:55.25,0:05:58.40,Default,,0000,0000,0000,,An example attack is DNS spoofing.
Dialogue: 0,0:05:58.40,0:06:01.72,Default,,0000,0000,0000,,That's when a hacker\Ntaps into a DNS server
Dialogue: 0,0:06:01.72,0:06:04.45,Default,,0000,0000,0000,,and changes it to match a domain name
Dialogue: 0,0:06:04.45,0:06:06.72,Default,,0000,0000,0000,,with the wrong IP address.
Dialogue: 0,0:06:06.98,0:06:11.59,Default,,0000,0000,0000,,This lets the attacker send\Npeople to one imposter website.
Dialogue: 0,0:06:11.59,0:06:13.36,Default,,0000,0000,0000,,If this happens to you,
Dialogue: 0,0:06:13.36,0:06:15.69,Default,,0000,0000,0000,,you are vulnerable for more problems
Dialogue: 0,0:06:15.69,0:06:19.78,Default,,0000,0000,0000,,because you are using that\Nfake website as if it is real.
Dialogue: 0,0:06:21.44,0:06:25.60,Default,,0000,0000,0000,,The internet is huge, and\Ngetting bigger every day.
Dialogue: 0,0:06:25.60,0:06:28.60,Default,,0000,0000,0000,,But the Domain Name System\Nand Internet Protocol
Dialogue: 0,0:06:28.60,0:06:30.48,Default,,0000,0000,0000,,are designed to scale,
Dialogue: 0,0:06:30.48,0:06:32.88,Default,,0000,0000,0000,,no matter how much the internet grows.