1.2 Understanding the OSI Model Flashcards
With windowing, the client adjusts ________________ amount of data sent in each segment as the number of retransmissions occur, and adjust to a ________________ amount of data sent in each segment as the number of retransmissions are eliminated.
lower
higher
_______________ allows us to take a big chunk of data and cut it up into smaller packets and send them all out in different directions. It allows the recipient to put the packet back together, and since it is sequenced can be put back together in order.
Packet reordering
You should think of a _________________ as a conversation that must be kept separate from others to prevent intermingling of the data.
session
In Packet Switching the data may take different paths from the client to the host during a session, in ______________ the data takes the same path from the client to the host during that session.
Circuit Switching
_________________ includes transfer of data across the network, reestablisment of a disconnected session, and acknoledgment of data received.
Maintaining a Session
What does OSI stand for?
Open Systems Interconnection Reference Model
The OSI serves as the ______________ model for a network.
reference
_________________ is used in Layer 6 to scramble the data in transit to keep it secure from prying eyes, and provide confidentiality of data.
Encryption
Most networks use ______________ switching because we have other methods to check if it is being sent to the other in, if not it will try other paths until the data gets there.
Packet
Layer 2 devices vew networks ______________.
logically
Layer 4 is for segments almost exclusively, but if your using UDP you are using a ________________.
datagram
Switches, the physical devices, are layer ______________ devices.
2
At the _________________ layer of the OSI model we are dealing with the IP addresses, any routing decisions being made here.
Layer 3 - Network
_________________ is where applications send out announcements to other devices on the network to state the services they offer. This can also be done by Active Directory if using it.
Service Advertisement
H.323 and H.264 are both used to Setup, maintain and tear-down _________________connections such as Skype or Facetime.
video
Another ICMP used is called _______________ which traces a route that a packet takes through the network and tell you every router along the way it goes through.
traceroute
________________ is the data type in the transport layer.
Segment
In layers 5, 6, and 7 data is called ______________.
data
ASCII, EBCDIC, and UNICODE all tell us how to get _________________ out of 1’s and 0’s.
text
There aren’t really Layer 5 _________________, mostly just protocols.
devices
_________________ involves checking of user credentials and assigning numbers to sessions to help identify them, which allows to negotiate service needed for that session and determine who begins sending data.
Setting up a Session
The SYN/SYN-ACK/ACK messaging of TCP is called the ________________.
Three-way handshake
The big question being answered at layer 3 is how data should be ______________ or ______________.
forwarded or routed
H.323 and H.264 both operate over the _________________ protocol.
RTP (Real-Time Protocol)
What are the 7 layers of the OSI model?
- Application
- Presentation
- Session
- Transport
- Network
- Data Link
- Physical
________________ allows the clients to adjust the amount of data sent in each segment and continually adjusts to send more or less data per segment transmitted.
WIndowing
_________________ is basically text, and 8 bit code that tells you what letter the code represents.
ASCII
The _________________ layer of the OSI model involves the signaling, cabling, connectors. (Cable, NIC, Hub)
Layer 1 - Physical
The Internet Protocol comes in two versions ______________ and ______________.
IPv4 and IPv6
Hubs, WAPs and Media Converters work at layer ______________ of the OSI model.
Physical Layer (Layer 1) (Dumb Devices)
NIC’s, Bridges, Swiches, and Mac Addresses are all Layer ______________ devices.
Layer 2 (Data Link)
At the _________________ layer of the OSI model handles a lot of the communication that will be encrypted and decrypted.
Layer 6 - Presentation
Our networks today work under the ______________ model.
TCP/IP
At the _________________ layer of the OSI model we find the control protocols, and tunneling protocols.
Layer 5 - Session
________________ is kind of like certified mail, you get proof that the data is delivered in full.
TCP
The _________________ layer, Layer _________________, provides application-level services and is where the users communicate with the computer.
Application Layer (Layer 7)
______________ is needed to prevent the sender from sending data faster than the recipient can accept it.
Flow control
Route discovery and selection is manually configured as a static route or dynamically through a ______________, which help decide which path data will take.
routing protocol
Numerous routed protocols were used for logical addressing over the years but only the ______________ remains dominant.
Internet Protocol (IP)
GIF, JPG, TIF SVG, and PNG all tell us how to get _________________ out of 1’s and 0’s.
graphics
At the _________________ layer of the OSI model shows what we see when using the application.
Layer 7 - Application
The ______________ layer packages data into frames and transmits those frames on the network, performing error detection/correction, uniquely identifying network devices with an address (MAC), and providing flow control.
Data Link Layer (Layer 2)
A ________________ works like a regular layer 2 switch and a layer 3 router combined.
multilayer switch
Layer 3 of the OSI model is all about ______________, and is known as the ________________ layer.
Routing
Network Layer
In layer 3 data is called ______________.
packets
_________________ and _________________ are level 6 encryptions algorithyms that takes the 1’s and 0’s and scrambles them up so noone else can read them.
TLS
SSL
Packet Switching is known as ______________, where data is divided into packets and forwarded.
routing
_________________ such as HTML, XML, PHP, and JavaScript are all Layer 6 (Presentation), because they tell ASCII how to display the text.
Scripting Languages
________________ is really good for audio and visual streaming because you send a lot of data, and there is a lot less overhead vs using TCP. You won’t notice dropped packets with streaming in UDP.
UDP
_________________ unite communicating components from more than one network application.
Application Services
Layer 7 email does not deal with applications like Outlook, but the _________________ applications of email such as POP3, IMAP, and SMTP.
lower-level
Do Some People Fear Birthdays
data - 7,6,5 segments - 4 packets - 3 frames -2 bits - 1
In layer 1 data is called ______________.
bits
POP3, IMAP, SMTP, HTTP, HTTPS, DNS, FTP, FTPS, Telnet, SSH, and SNMP are all application services used in Layer _________________.
Layer 7, Application Layer
Within the IP communication is the _________________ layer of the OSI model, we find the TCP/UDP protocols here.
Layer 4 - Transport
Layer 5 is the _________________ layer.
Session Layer
The most common protocols used in Layer 3 are ________________, ______________, and _____________.
IPv4 protocol
IPv6 protocol
Internet Control Message Protocol (ICMP)
IPv4 and IPv6 are both Layer ______________ protocols.
3
If a TCP segment is dropped, the protocol will ask for acknowledgment each and every time data is sent. If it does not get the acknowledgment it will resend the data. That’s why we call it a ________________ protocol.
connection full protocol
_________________ is done by the computer to have compatability between different devices.
Data formatting
With a ______________ routing protocol, all of the routers continually talk to each other to decide the best way for data to be routed from client to host.
dynamic
The _______________ protocol is used to send error messages and operational information about an IP desitnation.
ICMP (Internet Control Message Protocol)
TCP, UDP, WAN accelerators, Load Balancers, and Firewalls are all of examples of Layer _________________ protcols and devices.
Layer 4 Transport
_________________ is ending of a session due to mutual agreement (after the transfer is done) or when the other party disconnects.
Tearing Down a Session
______________ involves taking some limited amount of resource and using it more efficiently. Allows multiple users to use a baseband connection at the same time.
multiplexing
The two main protocols of the Layer 4 Tranport Layer, are ________________ and ________________.
TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)
The ________________ is the dividing line between the upper and lower layers of the OSI model.
Transport Layer (Layer 4)
_________________ occurs when devices, such as routers, allocate memory to store segments if bandwidth isn’t readily available.
Buffering
In ______________ data is divided into messages, similar to packet switching, except these messages may be stored then forwarded more like an email.
Message Switching
Layer 3 switching is called ______________.
routing
In layer 2 data is called ______________.
frames
In layer 4 data is called ______________.
segments
The _________________ layer, Layer _________________, is responsible for formatting the data exchanged and securing that data with the proper encryption.
Presentation Layer (Layer 6)
_________________ is used by computers to share files over a network, and by WIndows to share files on the inside.
NetBIOS
When you think of Layer 6 you should think about _________________ and _________________.
data formatting
data encryption
MP4, MPG, and MOV all tell us how to get _________________ out of 1’s and 0’s.
video
______________ is called different names as it flows though different layers of the OSI model.
data
_________________ provides encryption between your computer and websites, such as HTTPS.
TLS (Transport Layer Security)
In the _________________ layer of the OSI model we might find MAC addresses in the frame of communication, all of the switching decisions occur here.
Layer 2 - Data Link
Their is no sequencing, or aknowlegement with the ________________ protocol.
UDP
The most common examples of Layer 3 devices are ___________________ and _______________
Routers
Multilayer Switches
The most common ICMP used is called _______________, which sends out a single packet to a test to an IP address and tells you if it was received or not and how long it took.
ping
With TCP, the client sends a ________________ message asking if the server is ready for data, the server sends back a ________________ message saying it is ready to receive data, then the client sends a ________________ message notifiying that data is on the way.
SYN (synchronization)
SYN-ACK (synchronization acknowledgment)
ACK (acknowledgment)
