Transcript 1010 - Moodle

1010
Week 4
1010
1010
Computer Networks – IP addresses
and binary
Starter – complete the introduction by
matching the words with the numbered gaps,
write the number & word on your whiteboard
Computers can only represent ………(1)…….. using
1s and 0s. This number system is called
………(2)………..
This is because they are ………(3)……………. devices
and ………(4)..…………..is either …(5)….(=1) or …(6)….
(=0).
All devices connected to a network need an
…(7)….. address which to us would look something
like………………(8)……………………….
However, a computer can only recognise this when
it is converted to………(9)………… so that’s what
we’re doing today!
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In today’s lesson:
Lesson Objectives
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• Be able to convert to/from binary numbers
and write an IP address as a binary number
• Understand why devices need an IP address
• Understand the issue with the current format
of IP addresses
Success Criteria
 ALL: Successfully convert smaller numbers to/from binary. Understand
that each device connected to a network needs an IP address.
 MOST: Successfully convert IP addresses to and from binary. Be able to
explain why a device needs an IP address to connect to a network.
 SOME: Be able to explain why a new system of IP addresses has to be
used.
Literacy -Today’s key words
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Can you remember what an
IP address looks like?
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• An IP address is a 32-bit numeric address written as four bytes
separated by full stops (these are called octets).
• Each number can be 0 to 255.
• For example, 19.163.10.240 could be an IP address.
• Within your home network, your devices could be assigned IP
addresses at random as long as each one is unique. However,
connecting your home network or a server to the Internet via your
ISP requires using registered IP addresses (called Internet
addresses) to avoid duplicates.
• Some combinations such as 0000.0000.0000.0000 or
255.255.255.255 are restricted
IP addresses and binary
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• As computers only use binary, an IP address must
be stored as a binary number for the
computer/network’s use, but can is written as
numbers that we recognise for human users.
For example:
172
. 16 .
254
.
1
10101100.00010000.11111110. 00000001
Byte 1 (the network)
Byte 2
Byte 3
Byte 4 (the device)
You might need a refresher
on binary so here we go:
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We use Base 10 so everything goes up in 10s and we
can use all the numbers from 0 to 9
1000
100
10
1
0
1
6
8
= (0 x 10000) + (1 x 100) + (6 x 10) + (1 x 8) = 168
Binary uses Base 2 so everything goes up in 2s and only
uses 1 or 0.
128
64
32
16
8
4
2
1
1
0
1
1
0
0
1
0
=(1 x 128) + (0 x 64) + (1 x 32) + (1 x 16) + (0 x 8) + ( 0 X 4) ( 1 X 2) + ( 0 x 1) = 168
8
An Example
• The value of binary 01100001 is decimal 105. This is worked out below:
128
64
32
16
8
4
2
1
-------------------------------------------------------------------------------
0
1
1
0
1
0
0
1
1X1
0X2
0X4
1X8
0 X 16
1 X 32
1 X 64
0 X 128
Total them to get the Answer: 105
=1
=0
=0
=8
=0
= 32
= 64
=0
9
Another example
• The value of binary 10011100 is decimal 156. This is worked out below:
128
64
32
16
8
4
2
----------------------------------------------------------------------
1
1
0
0
0
1
1
1
0
0X1
0X2
1X4
1X8
1 X 16
0 X 32
0 X 64
1 X 128
Total them to get the Answer: 156
=0
=0
=4
=8
= 16
=0
=0
= 128
Binary Conversions
128
64
32
16
8
4
2
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1
Learning Check …Easy….
On your whiteboard, convert these numbers from binary to
denary:
1.1101
2.1001
3.1010
4.1000
5.0101
Binary Conversions
128
64
32
16
8
4
2
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1
Learning Check …Harder ….
On your whiteboard, convert these numbers from binary to
denary:
1.011101
2.101001
3.101010
4.011000
5.100101
Binary Conversions
128
64
32
16
8
4
2
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1
Learning Check …Hardest ….
On your whiteboard, convert these numbers from binary to
denary:
1.10011101
2.01101001
3.11101010
4.10011000
5.11100101
Binary Conversions
128
64
32
16
8
4
2
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1
Learning Check …Easy-ish….
On your whiteboard, convert these numbers from denary
to binary:
1.12
2.28
3.46
4.68
5.130
Binary Conversions
128
64
32
16
8
4
2
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1
Learning Check …Harder ….
On your whiteboard, convert these numbers from binary to
denary:
1.55
2.76
3.219
4.178
5.255
So how does this work with
IP addresses?
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How many IP addresses are
there?
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• This 32-bit IP address system is also known as IPv4. It allows for 2 32
or around 4 billion unique addresses. But ……
• There are currently billions of devices connected to the Internet.
This number is set to grow
with the increase in internet
capable smart devices and
machines (e.g. televisions,
air conditioners, washing
machines, lights, cars etc.).
All will have to connect and
communicate through some
form of IP Address.
There’s an IP Address shortage
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• While nearly 4 billion unique combinations might sound like a lot,
the huge growth in internet connected devices means we have
nearly run out of available IPv4 addresses.
• Most devices are “loaned” a dynamic IP address for a period of
time, apart from servers which get a static IP address that doesn’t
change.
• So, IPv6 is now coming into use. IPv6 uses 16 bits for each section
of the address, creating a 128-bit address. This allows for a
MASSIVE number of IP addresses – in fact, almost 80 octillion or a
thousand quadrillion or 1027 unique IP addresses.
What do IPv6 IP addresses
look like?
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• IPv6 addresses are 128-bit IP address written in
hexadecimal and separated by colons.
• An example IPv6 address could be written like this:
3ffe:1900:4545:3:200:f8ff:fe21:67cf
• As an extension task, you can find out more about
hexadecimal numbers, we’re not covering them today!!!
What to do now
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• Make sure you have a folder in your work area called
Computer Networks
• Log into Moodle
• Go to ICT & Computing > Year 8 > Digital Networks >
Week 4
• Download to your documents the worksheet called IP
Addresses and Binary (not to downloads, put it in your
correct folder!)
• Open it and complete it. Print by end of lesson!
Q6 answers
1. 88.70.244.38 = Vodafone, Germany
2. Microsoft
3. Amazon (actually it’s for intu the Trafford Centre, whose
website is hosted by them at that IP address)
4. 23.203.220.68 = McDonalds, America
Because websites are often on shared servers, a search to find information about
the IP address doesn’t necessarily give you the name of each company, it gives you
the name of the hosting company.
Also, an IP address may change, so it could be that an IP address won’t work
Not all IP addresses are listed in the databases used by the “lookup” tools online
Plenary – how well have you
done today?
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Which Success Criteria have you met?
Can you……?
 ALL: Successfully convert smaller numbers to/from
binary. Understand that each device connected to a
network needs an IP address.
 MOST: Successfully convert IP addresses to and from
binary. Be able to explain why a device needs an IP
address to connect to a network.
 SOME: Be able to explain why a new system of IP
addresses has to be used.