Local Area Networking Flashcards
ARPANET
basis for early internet
Adopted TCP/IP protocols
Types of IP Addresses
Class C - 210.11.12.x where you gets ranging from 210.11.12.1 - 210.11.12.254
Class B - 172.16.x.x
Class A - 6.x.x.x
Class D - 224.x.x.x (addresses for multicast)
Class E - 240.x.x.x
IP Addressing and what gets added to an Ethernet frame
Destination and source IP addresses get added to an Ethernet frame along with the destination and source MAC address, the data and the FCS (the frame check sequence)
Subnet Mask
255.255.255.0
Where you see a 255 the numbers have to be the same
where you see a 0 they can be different
By comparing another IP address with the subnet mask your computer can determine if it can send data to a local machine or to the router so it can go to another LAN
0 at the end of an IP address
Putting a 0 at the end of an IP address means your identifying an entire LAN and not a singular computer
Static IP Address
Manually entering an IP Address, the subnet mask and the default gateway
Private IP addresses
Class A 10.x.x.x
Class B 172.16.x.x - 172.31.x.x
Class C 192.168.x.x
Loopback Address
127.0.0.1
Refers to your own system
NAT (Network Address Translation)
Instead of every computer getting an IP address, we can assign an IP address to a router for a LAN and then assign private IP addresses to private computers on the LAN
When your router gets data to be sent to the internet, it will change the destination and source IPs on the frames to your LAN’s public IP addresses
DHCP (Dynamic Host Configuration Protocol)
Dynamically assigns IP addresses to computers that connect to the network
APIPA (Automatic Private IP Addressing)
Found on pretty much all Operating Systems.
Basically the fallback if you can’t find a DHCP server
- Will always give a 169.254.X.X address
Class B - 255.255.0.0 Subnet Mask
ipconfig /renew
a command that forces a new connection the DHCP Server
IPv6
8 Groups of 4 characters seperated by 7 colons
2001:0000:0000:0001:0000:0000:0000:8a2e
Short Hand
2001:0:0:1:0:0:0:8a2e (Replace 0000 w/ 0 and 0001 w/ 1)
2001:0:0:1::8a2e (replace 0:0:0 with ::)
Uses a 128-bit Addressing Scheme
Hexadecimal
Link-Local Address
Always starts with fe80:0000:0000:0000
the last half is auto generated by the computer
Port Number
0-65535
How computers know which application is send and receiving data
Source and destination port number on Ethernet Frame
to and from port numbers and IPs get swapped when coming back
IP addresses get frames to the right computer but ports get it to the right application
Types of Ports
Ports 0-1023 - Well Known
Ports 1024-49151 - Registered Ports
Ports 49152-65535 - Dynamic/Ephemeral
Protocol
Set of rules that allow different things to work together
TCP / IP
Transmission Control Protocol / Internet Protocol
TCP - Connection Based Protocol
Protocol that establishes a connection between client and server first called a Handshake
UDP - Connectionless Protocol
No handshakes like TCP just sends data without a hello
ICMP
Single Packet Only
Example - Ping
Protocol Data Unit (PDU)
Ethernet Frame:
Full frame with mac addresses and FCS
IP Packet:
IP addresses, ports and data
TCP Segment/UDP Datagram:
Ports and Data
Domain Name System (DNS)
Replaced Host Files
Root servers - “.”
First level domains - “.com”, “.edu”, “.gov”
Second level domains - “totalsem.com”, “google.com”
When you type in an URL you will connect to a DNS server that checks if it has an IP address for the website
ipconfig /all to view DNS server
Fully qualified domain name (FQDN)
256 Character Limit
Taking a unique domain address and getting it registered to a DNS server
nslookup
Tool that checks if a DNS server is up and legitimate
You can select a DNS server, local or not, and query domain IPs to test if a certain DNS server is up and runnign correctly
