Day 1 - Networks, Cables, OSI, and TCP Models Flashcards
1
Q
What does
All People Seem To Need Data Processing
stand for?
A
Application Presentation Session Transport Network Data Link Physical
2
Q
Application layer #?
A
7
3
Q
Presentation layer #?
A
6
4
Q
Session layer #?
A
5
5
Q
Transport layer #?
A
4
6
Q
Network layer #?
A
3
7
Q
Data Link layer #?
A
2
8
Q
Physical layer #?
A
1
9
Q
What is the OSI model mnemonic?
A
All People Seem To Need Data Processing
10
Q
What is the process of data moving down the OSI model called?
A
Encapsulation
11
Q
What is the process of data moving up the OSI model called?
A
De-encapsulation
12
Q
Define the Application Layer (7)
A
This layer is the closest layer to the end-user. The Application Layer usually provides services such as e-mail (SNMP and POP3), web browsing (using HTTP), and file transfer services (using FTP). The Application Layer determines resource availability.
13
Q
Define the Presentation Layer (6)
A
The Presentation Layer presents data to the Application Layer. Multimedia works here, so think mp4, jpeg, gif, etc. Encryption, decryption, and data compression also take place at this layer.
14
Q
Define the Session Layer (5)
A
The role of the Session Layer is to set up, manage, and terminate sessions or dialogues between devices. These take place over logical links, and what is really happening is the joining of two software applications. SQL, RPC, and NFS all work at the Session Layer.
15
Q
Define the Transport Layer (4)
A
The role of the Transport Layer is to break down the data from the higher layers into smaller parts, which are referred to as segments (at this layer). Virtual circuits are set up here, which are required before devices can communicate.
16
Q
What are the three methods used to control data flow?
A
▪ Flow control
▪ Windowing
▪ Acknowledgements
17
Q
What is Flow Control?
A
If the receiving system is being sent more information than it can process, it will ask the sending system to stop for a short time. This normally happens when one side uses broadband and the other uses a dial-up modem. The packet sent telling the other device to stop is known as a source quench message.
18
Q
What is Windowing?
A
With windowing, each system agrees upon how much data is to be sent before an acknowledgment is required. This “window” opens and closes as data moves along in order to maintain a constant flow.
19
Q
What are Acknowledgements?
A
When a certain amount of segments is received, the fact that they all arrived safely and in the correct order needs to be communicated to the sending system.
20
Q
What is the Three-Way Handshake?
A
This is where you send a packet to establish the session. This first packet is called a synchronise (SYN) packet. Then the remote device responds with a synchronise acknowledgement (SYN-ACK) packet. The session is established in the third phase when an acknowledgement (ACK) packet is sent.
21
Q
Which service does the Three-Way Handshake use?
A
TCP service
22
Q
What are the two most widely known Transport Layer protocols?
A
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
23
Q
What are the main characteristics of TCP
A
Reliable connection-oriented protocol
Uses three-way handshake
Uses windowing
24
Q
What protocols use TCP?
A
Telnet
HTTPS
FTP
25
What are the main characteristics of UDP?
Connectionless protocol
Smaller packets
Conserves time and network resources
26
What is an example of a protocol that uses UDP?
TFTP
27
Define the Network Layer (3)
The Network Layer takes the segments from the Transport Layer and breaks them down into smaller units called packets. The Network Layer must determine the best path to take from one network to another; for this reason, routers work at this layer. Routers use logical addressing here, and TCP/ IP addressing is called IP addressing.
28
Define the Data Link Layer (2)
The Data Link Layer chops down packets into smaller units referred to as frames. Layer 2 switches work at this layer and use hardware or MAC addresses, so they can switch traffic much faster because there is no need to check IP addresses and routing tables. WAN protocols work at Layer 2, including HDLC, ISDN, and PPP. Ethernet also works at Layer 2. In order to interface with the upper and lower levels, the Data Link Layer is further subdivided into the Logical Link Control (LLC) Sublayer and the Media Access Control (MAC) Sublayer. The LLC Sublayer interfaces with the Network Layer and the MAC
29
Define the Physical Layer (1)
At this layer, frames are converted into bits for placing on the wire. These bits consist of electrical pulses, which are read as “on” and “off” bits, or in binary 1s and 0s, respectively. Hubs work at this layer, and here is where you will find cable specifications, such as RJ45.
30
What is the four layer TCP/IP DoD Model?
Application (4)
Transport/Host-to-Host (3)
Internet or Internetwork (2)
Link/Network Interface (1)
31
What is the five layer TCP/IP DoD Model?
```
Application (5)
Transport (4)
Network (3)
Data Link (2)
Physical (1)
```
32
What is the encapsulation and data called at the Application Layer?
Data, but not encapsulated yet.
33
What is the encapsulation and data called at the Transport Layer?
TCP header added to the data.
Data is called a Segment
34
What is the encapsulation and data called at the Network Layer?
IP header added (including IP address).
Data is called a Packet
35
What is the encapsulation and data called at the Data Link Layer?
Data Link header added (Data Link address).
Data is called a Frame
36
What is the encapsulation and data called at the Physical Layer?
Data is turned into electrical signals.
Data is called Bits on the wire
37
What is TCP/IP?
TCP/ IP is a complete suite of protocols and services which enable communication to take place over networks.
38
What layer does TCP operate at in the OSI model?
Transport Layer
39
What is the TCP port for FTP Data?
20
40
What is the TCP port for FTP Control?
21
41
What is the TCP port for SSH?
22
42
What is the TCP port for Telnet?
23
43
What is the TCP port for SMTP?
25
44
What is the TCP port for DNS?
53
45
What is the TCP port for HTTP?
80
46
What is the TCP port for POP3?
110
47
What is the TCP port for NNTP?
119
48
What is the TCP port for NTP?
123
49
What is the TCP port for TLS/SSL?
443
50
At what OSI layer does Internet Protocol (IP) operate?
Network Layer
51
Define Internet Protocol (IP)
IP operates at the Network Layer of the OSI model. It is connectionless and is responsible for transporting data over the network. IP addressing is a function of Internet Protocol. IP examines the Network Layer address of every packet and determines the best path for that packet to take to reach its destination.
52
Define User Datagram Protocol (UDP)
UDP transports information between network devices but, unlike TCP, no connection is established first. UDP is connectionless, gives best-effort delivery, and gives no guarantee that the data will reach its destination.
53
At what OSI level does User Datagram Protocol (UDP) operate?
UDP operates at the Transport Layer of the OSI model.
54
Both TCP and UDP are carried over what protocol?
IP
55
When is UDP preferred over TCP?
For applications in which low latency is preferred over reliability or guarantees.
56
What are three common UDP protocols and their related port numbers?
DNS 53
TFTP 69
SNMP 161/162
57
At what OSI layer does FTP operate at?
Application Layer
58
What protocol does FTP use for data transfer?
TCP
59
What is the command to debug FTP traffic?
debug ip ftp
60
What protocol does SMTP use?
TCP
61
What is the command to debug HTTP traffic?
debug ip http
62
What is the only utility that can check all seven layers of the OSI model?
Telnet
63
What is the command to quit an inactive telnet session?
Ctrl Shift 6 then X
64
What is the debug command for Telnet?
debug telnet
65
What does ICMP stand for?
Internet Control Message Protocol
66
What is ICMP used for?
ICMP is a protocol used to report problems or issues with IP packets (or datagrams) on a network.
67
What happens when a problem is experienced with an IP packet?
The IP packet is destroyed and an ICMP message is generated and sent to the host that originated the packet.
68
ICMP delivers messages inside ?
IP packets
69
What type of packet does a ping command generate?
An echo request packet
70
What does TTL stand for?
Time to Live
71
What are the keyboard commands to terminate a ping session?
Ctrl Shift 6 then X
72
What type of packets does Traceroute use?
UDP
73
What are the two types of addressing used to identify network hosts and their layers?
IP addressing (Network/Layer 3)
MAC address (Data Link/Layer 2)
74
Explain address resolution
The process in which the IOS determines the Data Link Layer address (MAC address) from the Network Layer address (IP address)
75
Define ARP
Address Resolution Protocol resolves a known IP address to a MAC address.
76
If a host does not have the destination host's MAC address in its ARP cache what does it do?
Sends out an ARP Broadcast message
77
Define Proxy ARP
Proxy ARP enables hosts on an Ethernet network to communicate with hosts on other subnets or networks, even though they have no knowledge of routing.
78
Do routers forward ARP Broadcasts by default?
No
79
What is the proxy ARP command?
ip proxy-arp
80
What is RARP?
Reverse Address Resolution Protocol
Maps a known MAC address to an IP address
81
What is GARP?
Gratuitous Address Resolution Protocol
A gratuitous ARP request is a special ARP request packet where the source MAC, the source IP, and the destination IP addresses are all set to the IP address of the machine issuing the packet, and the destination MAC is the Broadcast address FFFF: FFFF: FFFF.
82
When does a normal host send out a GARP request?
After the link goes up or the interface is enabled
83
If you see a GARP reply what does that mean?
Another computer on the network has the same IP address as you do
84
What is SNMP?
Simple Network Management Protocol
85
What are the SNMP messages that network devices send to management stations called?
Traps
86
What does HTTPS stand for and what are the two protocols used?
Hyper Text Transfer Protocol Secure
TLS and the older protocol SSL
87
10Mbps is known by what name?
Ethernet
88
100Mbps is known by what name?
FastEthernet
89
1000Mbps is known by what name?
GigabitEthernet
90
10Gbps is known by what name?
TenGigabitEthernet
91
What does half duplex mean?
Data can only pass in one direction on the wire at a time
92
What does full duplex mean?
Data can pass in both directions on the wire at the same time.
93
What is the command to check an interface's duplex settings?
show interface X
94
If each pin on one end of an RJ45 cable matches the other side then this is known as a ?
straight-through cable
95
What type of RJ45 cable would you need to connect an end device to an Ethernet port on a switch?
straight-through cable
96
What type of RJ45 cable would you need to connect a switch to a router?
straight-through cable
97
What type of RJ45 cable would you need to connect a pc to a pc?
crossover cable
98
What type of RJ45 cable would you need to connect a switch to a switch?
crossover cable
99
How does a crossover cable differ from a straight-through cable?
Two of the wires on the cable have been swapped.
1 to 3
2 to 6
4,5,7,8 stay the same
100
"Flat" cables and "rollover" cables are examples of ?
console cables
101
What are the typical characteristics of a console cable?
All pins/wires are swapped so 1 to 8, 2 to 7, etc.
They usually have an RJ45 connection on one end and a 9-pin D-Shaped connection on the other end.
102
What does DTE stand for?
data terminal equipment
103
What does DCE stand for?
data communications equipment
104
A DB60 is an example of what type of cable?
Wide Area Network (WAN)
105
Which end of a DB60 cable plugs into the customer equipment?
DTE
106
Which end of a DB60 cable plugs into the ISP connection?
DCE
107
What is the most important thing to remember about DCE and DTE cables?
You need to apply a clock rate to the DCE end in order for the line to come up.
108
What is the command to establish which router has the DCE cable attached?
show controllers
109
What is the command to see which interfaces you have on your router?
show ip interface brief
110
What is the first mode you will be presented with when the router boots?
User mode
111
User mode is also known as?
User Exec mode
112
What is the command to take you from User mode to Privileged mode?
enable
113
Privileged mode is also known as?
Privileged Exec mode
114
What mode do you need to be in to configure the router?
Global Configuration mode
115
What is the command to enter Global Configuration mode?
configure terminal
116
What mode do you need to be in to enter Global Configuration mode?
Privileged Exec mode
117
What are the two main types of commands you can use in Privileged Exec mode?
show and debug
118
To make changes to the console, Telnet or auxiliary ports you need to be in what mode and what is the command?
Line Configuration mode
config t
line [type] X
119
To configure a routing protocol on a router what mode do you need to be in and what is the command?
Router Configuration mode
config t
router rip
120
How do you enter VLAN Configuration mode?
config t
| vlan X
121
What key combination will exit the current configuration mode?
Ctrl Z
122
Keystrokes for moving to the beginning of the command line?
Ctrl A
123
Keystrokes for moving to the end of the command line?
Ctrl E
124
Keystrokes for moving back one character?
Ctrl F
125
Keystrokes for moving back one word?
Esc B
126
Keystrokes for moving forward one word?
Esc F
127
Keystrokes for recalling the previous command?
Ctrl P or up arrow
128
Keystrokes for recalling the next command?
Ctrl N or down arrow
129
Keystrokes to delete a line?
Ctrl U
130
Keystrokes to delete a word?
Ctrl W
131
Keystroke to finish a command?
Tab
132
Command to show last 10 (by default) commands entered?
show history
133
Keystrokes to delete a single character?
Backspace
134
Interfaces locations on routers are identified by ?
Module
Slot
Port
135
What are the most common router and switch interfaces used in modern enterprise networks?
100Mbps--FastEthernet
1Gbps--GigabitEthernet
10Gbps--TenGigabitEthernet
136
What are the three parameters that must be configured on a router interface for basic functionality?
Speed
Duplex
IP address
137
What is the command to enter Interface Configuration mode?
config t
| interface [interface name]
138
What is the first step and related command in the interface configuration process?
enable the interface
no shutdown
139
To configure the IP address on an interface what is the command?
config t
interface [interface name]
ip address [ip address] [subnet mask]
140
What is the command to add a description/label to an interface?
description [description]
141
What is the command to show the configuration in DRAM?
show running-configuration
142
What is the command to show the configuration in NVRAM?
show startup-configuration
143
What is the command to show which IOS is in flash?
show flash:
144
What command shows a summary of all interfaces?
show ip interface brief
145
What command shows statistics for a specific interface?
show interface [interface name]
146
What are the five variables for the method parameter on an interface?
```
unset
manual
NVRAM
IPCP
DHCP
```
147
What is the command to increase the history buffer?
terminal history size [size]
148
What information does the Show Version command provide? (8)
```
type of router
IOS version
Memory capacity
Memory usage
CPU type
Flash capacity
Other hardware parameters
Reason for last reload
```
149
What is the command to list all the networks the router can reach and information about the way they can be reached?
show ip route
150
The show ip route command includes what specific information? (4)
Network
Routing protocol
Next Hop
Outgoing interface
151
Name each layer of the OSI model, from Layer 7 down to Layer 1.
Application, Presentation, Session, Transport, Network, Data Link, and Physical.
152
The role of the Session Layer is to _______, _______, and _______ sessions or dialogues between devices.
Set up, manage, and terminate.
153
What are the three methods used to control data flow at Layer 4?
Flow control, windowing, and acknowledgements.
154
The Transport Layer includes several protocols, and the most widely known are _______ and _______.
TCP and UDP.
155
Why is UDP used at all if TCP/ IP offers guaranteed delivery?\
TCP uses a lot of bandwidth on the network and there is a lot of traffic sent back and forth to set up the connection, even before the data is sent. This all takes up valuable time and network resources. UDP packets are a lot smaller than TCP packets and they are very useful if a really reliable connection is not that necessary. Protocols that use UDP include DNS and TFTP.
156
What is data referred to at each OSI layer?
Bits (Layer 1), Frames (Layer 2), Packets (Layer 3), Segments (Layer 4) and Data (Layers 5-7).
157
In order to interface with the upper and lower levels, the Data Link Layer is further subdivided into which two Sublayers?
LLC and MAC.
158
What are the five TCP/ IP layers from the top down?
Application, Transport, Network, Data Link, and Network.
159
How does the TCP/ IP model map to the OSI model?
Write out.
160
Layer 2 addresses are also referred to as _______ addresses.
MAC
161
Using a switch will allow you to divide your network into smaller, more manageable sections known as _______ _______.
Collision domains.
162
The current standard Ethernet cable still uses eight wires twisted into pairs to prevent _______ _______ and _______.
Electromagnetic interference (EMI) and crosstalk.
163
_______ is when a signal from one Ethernet wire spills over into a neighbouring cable.
Crosstalk.
164
Which command would set the FastEthernet router interface speed to 10Mbps?
The speed 10 command.
165
On a crossover cable, the wire on pin 1 on one end needs to connect to pin _______ on the other end and pin 2 needs to connect to pin _______.
3 and 6.
166
Which cable would you use to connect a router Ethernet interface to a PC?
A crossover cable.
167
You can see a summary of which interfaces you have on your router with the show _______ _______ _______ command.
ip interface brief
168
Line Configuration mode lets you configure which ports?
The console, Telnet and auxiliary ports.
169
A Loopback interface is a _______ or _______ interface that you configure.
Virtual or logical
170
The keyboard shortcut Ctrl + A does what?
moves the cursor to the beginning of the command line
171
The _______ keyboard shortcut moves the cursor back one word.
Esc B
172
By default, the _______ _______ command shows the last 10 commands entered.
show history
