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Title: CompTIA Network+ - TCP/IP Basics
Description: CompTIA Network+ certification notes. Notes also work for any general networking class.
Description: CompTIA Network+ certification notes. Notes also work for any general networking class.
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Introduction to IP Addressing and Binary
Monday, November 02, 2015
-
8:02 AM
Every computer must have a unique IP address
...
Dots don't exist in IP addresses, just separators
...
Dotted Decimal Notation A short cut to represent 32 ones and zeros
...
Binary to Decimal:
To convert binary to dotted decimal notation, use the binary place value chart
...
1
0
0
1
0
1
1
0
0
0
1
1
1
0
1
1
1
1
1
1
128 + 16 + 4 + 2 = 150
10010110 = 150
0
0
8 + 4 + 2 = 14
00001110 = 14
1
1
128 + 64 +32 + 16 + 8 + 4 + 2 + 1 = 255
11111111 = 255
255 is maximum dotted decimal notation value
...
128
64
32
16
8
4
2
TCP IP Basics Page 1
1
Going from left to right, take your decimal number and see whether the binary place value goes into it
or not
...
Then, subtract your decimal number with the place value and then see if that new decimal number is
bigger than the next place value number
...
But you
don't have their MAC address, you have to use ARP
...
After the destination computer responds with their MAC address, your computer stores that MAC
information into the ARP cache
...
Arp -a
To access ARP cache
- ARP resolves IP addresses
- ARP requests are broadcasts over a network
TCP IP Basics Page 3
Subnet Masks
Wednesday, November 04, 2015
8:54 AM
ARP is a great tool to get MAC addresses when you have a known IP address
...
When a frame wants to be sent out through a router, you cannot use ARP
...
Default
Gateway
IP address of the router itself
...
ARP is used when you are on a LAN but when you need to use a router, you use the default gateway
...
When a computer wants to send a frame out, first it checks the destination IP address
...
To be on the same
network, everything in the first 24 bits has to be the same (First three octets)
...
Network ID First three octets of network information
...
X)
Host ID
The unique information in the 4th octet of the network information
...
X
...
HOST ID)
You can never use the Host ID 0, or 255 in a IP address
...
255
Broadcast IP address
...
If the network ID is different, it sends an ARP to the router to determine the router's (default gateway)
MAC address
...
The bigger your
subnet mask, the less bits you have to work with
...
0
...
0, you can have 24 bits of IP address combinations
...
255
...
0, you only have 8
bits worth of IP address combinations (254 computers on a 8 bit subnet)
...
Home routers have an actually public IP address given to it by the Internet
service provider
...
They have a different type of IP address called a Private IP address
...
The IANA is located in the united states, and keeps track of every IP address in the world
...
They start out by passing out large chunks of IP addresses
to the Regional Internet Registries
...
Each RIRs is usually in charge of their continent
...
And within these regions, the RIRs pass out chunks of IP addresses to
Internet Service Providers
...
Each customer usually has one public IP address to get out on the internet while
the router assigns LAN IP addresses (Private IPs)
...
Back in the late 1970s, when the internet was just getting started, they only thought that there would be
10,000 computers at tops
...
But
now since there are only 4 Billion IPv4 Addresses, and a world population of over 7 Billion, they have to
carefully distribute public IP addresses
...
Class Licenses A way of organizing IP addresses, determined by the first octet of the IP address
...
Class A
/8 Bits, or WACK 8 Network ID (255
...
0
...
First Octet consists between 1-126
...
Only very large ISPs and companies can get Class A's
...
(255
...
0
...
First Octet consists between 128-191
...
Most ISPs will have this class
...
Most ISPs will have this class
...
255
...
0)
...
This is the most
common class and also the smallest
...
But they are reserved for broadcasting and
experiments
...
TCP IP Basics Page 6
Subnetting With CIDR
Wednesday, November 04, 2015
8:56 AM
Subnet Mask
11111111 111111111 111111111 000000000
255
255
255
/24
0
Network ID
Host ID
11010000
01010001
10111110
000000000
208
190
121
0
Subnet Mask
11111111
111111111 111111111 1
0000000
255
255
128
255
Network ID
/25
Host ID
11010000
01010001
10111110
208
190
0
0000000
121
1111111
Subnet Mask
11111111
111111111 111111111 1
0000000
255
255
/25
128
255
Network ID
Host ID
11010000
01010001
10111110
208
190
121
CIDR
0
0000001
1111110
Classless Inter Domain Routing
CIDR Notation WACK or the /network bits
- Subnet masks must be a string of Ones, followed by a
string of Zeros
...
But increasing the mask by 2 bits (WACK 26)
- 255
...
255
...
TCP IP Basics Page 7
A formula for determining the amount of subnets you need:
2^N = X Where N is the number of subnets you want
...
190
...
0
Keep adding more network bits until you have enough for 10
computers on each subnet
...
TCP IP Basics Page 8
More CIDR Subnetting Practice
Wednesday, November 11, 2015
9:04 AM
Example Question:
Network ID - 163
...
6
...
255
...
0 /24
By adding two network bits, you are creating four different subnets
...
255
...
192
Example Question:
Can you create 16 networks that support 7 computers each?
First, try out adding network bits to the subnet mask
...
/28
2^4 = 16
16 - 2 = 14
Yes you can
...
You will have 30 different hosts, 2^3 = 8, 32-2 = 30
...
- The number of hosts is inverse to the number of subnets
...
TCP IP Basics Page 9
Dynamic and Static IP Addressing
Wednesday, November 11, 2015
9:15 AM
Every computer on your IP network needs to have IP settings
...
Static
You type all the IP information manually and the computer stays with that information
...
DHCP
Dynamic Host Configuration Protocol
BOOTP Bootstrap Protocol
When your computer first starts up, it doesn’t have any IP information at all
...
DHCP is usually used as a server, it can be used with special software or it is usually used on a home
router
...
When your computer first stars up, it sends out a DHCP Discover broadcast on the MAC address (FF-FFFF-FF-FF-FF), and looks for a DHCP server
...
It then sends a
unicast DHCP offer to your computer
...
When your computer sees this Offer, it sends out a DHCP request back to the server
...
Once the DHCP server sees this, it sends back a DHCP Acknowledge
...
Each broadcast domain must have only one DHCP server
...
Ifconfig
IP configuration command on Linux
Ipconfig /all Complete IP configuration on Windows
...
Ipconfig /release Gets rid of DHCP server obtained information
...
There is a huge difference between a router DHCP server and a software DHCP server
...
Scope
A range of IP addresses that your DHCP server assigns
...
When DHCP goes down, It's hard to troubleshoot
...
It assigns you an APIPA
...
APIPA is built into all DHCP clients and is designed as a fallback in case your DHCP ever dies
...
254
APIPA Address 169
...
If there isn't a problem with the physical, then there probably is a problem with the DHCP server
...
Rogue DHCP
server
When you pick up a IP address from your DHCP server that isn't what you configured it
to be
...
- If you get an APIPA address, check to see if you are connected to a DHCP server
...
TCP IP Basics Page 12
Special IP Addresses
Wednesday, November 11, 2015
10:28 AM
Special IP addresses are IP addresses with special circumstances
...
254
...
X
DHCP server fallback
...
0
...
1
Network loopback IP, for testing NIC connections
...
X
...
X /8
Works on private networks, not the internet
...
16
...
X /16
192
...
X
Title: CompTIA Network+ - TCP/IP Basics
Description: CompTIA Network+ certification notes. Notes also work for any general networking class.
Description: CompTIA Network+ certification notes. Notes also work for any general networking class.