Futanals Flashcards
What does the physical layer use?
Bits (no shits!)
What are the types is network media
Copper
Fiber
Wireless
UTP types
Strait through
Crossover
Rollover
Fiber modes
Single mode
Multi mode
What is CSMA/CA
Collision detect Shared medium Listen till medium is not busy When collision ever one pulls out Random timer to resend
What is CSMA/CA
Collision avoidance
Waits till medium is not busy
Used today
Name the frame structure
[Dest Mac] [Source Mac] [T/L] [Data] [FCS]
Give me that MAC address deets
48 bit hex
Burnt in
How does the ARP table work?
Connects dest macs and ports.
Maintains and updates in real time
If Mac is not known it broadcasts
What is a trunk?
Trunk Is a path switches that takes multiple vlans using a tag system
Protocol 802.1q
STP STEPS
- Select Root switch
- Select Root port
- Select designated/ blocked ports
Ip characteristics
Wireless
Media independent
Best effort
32 bit dotted decimal
IPv4 header
Version
TOS type of service
TTL Time to live
Protocol
What is the Ip structure?
First half is the network, second half is host
IP address class ranges
Class A: 0-127 Class B: 128-191 Class C: 192-239
Ip private addresses
Class A: Every thing in the 10.0.0.0 Class B: 172.16.0.0 172.31.255.255 Class c: 192.168.0.0 192.168.255.255
What layer is DHCP and what does it do?
Layer 3 network
Gets the hosts IP address from the DHCP server
How does DHCP work?
Discover -host sends request for DHCP sequence Offer -DHCP offers a ip Request -host requests to use ip Acknowledge -DHCP affirms the lease
What is routing used for?
To reach hosts on other networks
What is NAT
Network address translation
Conserves IPv4 addresses
What is RIP and OSPF
A routing protocol used to exchange info about networks to calculate the best path
How does RIP work
Uses distance vectors
(Routers only know what there neibors tell them)
Sends all RIP routes every 30 sec
Based on metric hop count
How does OSPF work
Open shortest path first LinkState -all info sent to all routers -all routers have a complete map Based on areas Based on link speed
OSPF neighbors
OSPF routers send a hello every 10 sec. if no reply after 40 sec neighbor is dead
How long is a IPV6 address?
128
64 host
64 net
Link local unicast address
FE08::/10
IPv6 global unicast structure
(x) x.x.x.x
Global routing prefix
Subnet
Interface ID
What does the transport layer do?
Responsible for delivery of segments.
Uses ports
What’s the point of point #
Port # used by TCP and UDP TO tell the difference between applications
Characteristics of TCP
Provides reliable delivery
Stageful
Segments and reassembles data segments.
Flow control
Layer 4
How does TCP reliable
Each byte is given a sequence # uses to reassemble
Destination replay with the ACK to acknowledge right amount
TCP header fields
Port #
Sequence #
Acknowledgement #
Window size
Explain the TCP 3 way handshake
Computer A sends a syn1
Comp two returns an ack of 2 and a syn of 1 comp A returns a syn and ack of 2
What is tcp window size
TCP uses window size to manage data
What is UDP
It is a connection protocol that is faster then TCP and cheaper but lacks many of the features TCP has
Layer 4
What port is HTTP
80
What is FTP and what layer is it on?
File transfer protocol
Used to send it copy files from a server
Port 20-21
What is telnet?
Commands and data sent as plain text
What is SSH
Commands and data are encrypted
Email its ports and its protocols
SMTP 25
POP3 110
IMAP143
What layer is DNS and what does it do?
Domain name system
It translates the host name you typed in to an IP address
Layer 7 application
