csc Flashcards
1
Q
Command:
nslookup
A
Name System lookup, queries the DNS server to return an IP
2
Q
Command:
enable
A
Change from User Exec mode to Privileged mode
3
Q
Command:
configure terminal
A
Change from Privileged mode to global Configuration mode
4
Q
Command:
exit
A
Exit the current mode to the previous one, or log out if at the beginning mode.
5
Q
Command:
do
A
Allows you to run a non-config command while in config mode.
6
Q
Command:
no
A
Undoes a configuration
7
Q
Command:
hostname (name)
A
Change the hostname of the Cisco device
8
Q
Command:
ip domain-name (name)
A
Change the domain name of the Cisco device
9
Q
Command:
logging synchronous
A
Make it so a CLI does not interrupt a command while it is being typed if a debug message is received
10
Q
Command:
(config-line)
password
A
Require and define a password to access the selected line
11
Q
Command:
(config-line)
secret
A
Require and define a password that is hashed to access the selected line.
12
Q
Command:
(config-line)
login local
A
Use the local database to login to this line instead of a defined password/database for this line specifically.
13
Q
Command:
(config-line)
transport input (input)
A
Selects which protocols are allowed to access this line.
14
Q
Command:
enable password
A
Require and define a password to enter Privileged mode.
15
Q
Command:
enable secret
A
Require and define a password that is hashed to enter Privileged mode.
16
Q
Command:
service password-encryption
A
Encrypts new passwords within the device.
17
Q
Command:
clock timezone (timezone name) (hours from UTC)
A
create or configure a timezone to be used on the device
18
Q
Command:
ip route (destination) (mask) (next hop/exit interface)
A
adds a static entry to a device’s routing table.
19
Q
Command:
router (protocol) (number)
A
Enter the router dynamic routing protocol configuration mode
20
Q
Command:
router ospf (number)
A
enter configuration mode for OSPF on a router
21
Q
Command:
(config-router)
auto-cost reference-bandwidth (number)
A
configure the reference bandwidth for OSPF.
22
Q
Command:
(config-router)
network (network IP) (Wildcard mask) area (area number)
A
Enables OSPF on all interfaces within the defined network and designates its area number.
23
Q
Command:
show ip interface brief
A
Shows all network interfaces, their IP addresses, if they are OK, what method they use to connect, their status, and their protocol.
24
Q
Command:
show ip route
A
Shows a routing table in a router
25
Command:
show inventory
Gives information of the hardware name, revision, product ID, serial number, and others.
26
Command:
show tech-support
outputs a lot of information on the device. used for Cisco tech support.
27
Command:
show protocols
outputs the line status and protocols for all interfaces
28
Command:
show ip protocols
outputs the Dynamic Routing Protocols currently running on the device.
29
Command:
show clock
Return the current time.
30
Command:
show flash
Show files saved on flash, which will include the operating system.
31
Command:
show ip route
Show the routing table currently in use by the device
32
Command:
show ip ospf neighbor
Shows the OSPF table of neighbors within a router.
33
WAN
Wide Area Network - A network that consists of more than one LAN
34
WLAN
Wireless LAN - A LAN that is connected via Wireless means, such as Wi-Fi
35
SOHO
Small Office/Home Office - A SOHO device would be a device that functions as many networking devices.
36
IP
Internet Protocol
37
DHCP
Dynamic Host Configuration Protocol - A protocol used to assign IP addresses to clients from a server.
38
DNS
Domain Name System - Translates hostnames to IP addresses
39
Cisco IOS
Internetwork Operating System - Cisco operating system for Cisco network devices.
40
OSI Model
Open System Interconnection - 7 Layer model used as a standard of describing levels of networking.
41
PoE
Power over Ethernet - Allows Electrical Current over an Ethernet cable. Two standards, IEEE 802.3af (16.8 Watts) and 802.3at (PoE+, 16.8 Watts)
42
SFP
Small Form-factor Pluggable - Transceivers used to connect network devices to different types of cables, usually fiber.
43
CSMA/CA
Carrier Sense Multiple access with Collision Avoidance - Check if it is okay to send data, if it is, send it. Used for wireless networks.
44
CSMA/CD
Carrier Sense Multiple access with Collision Detection - Send data and detect if any collisions occur. Full duplex and switches make this obsolete.
45
CDP
Cisco Discovery Protocol - Cisco proprietary discovery protocol used to find directly linked devices.
46
LLDP
Link Layer Discovery Protocol - Standard protocol used to find directly linked devices.
47
RIP
Routing Information Protocol - Dynamic Routing Protocol, uses a count of hops on a network path for the metric.
48
EIGRP
Enhanced Interior Gateway Routing Protocol - Dynamic Routing Protocol, uses a calculation for a metric. Cisco Proprietary. The calculation is based on Bandwidth, Load, Delay, and Reliability.
49
Access point
A device that bridges connection between wireless and wired networks.
50
Controller
A device that centralizes operations for admin tasks to other connected devices.
51
SOHO Router
A device that functions as many devices, such as a firewall, router, Access Point, and switch.
52
IP Address
An address used to identify a network device, unique within a network. IPv4 Address - 32 bits (4 octet/byte), IPv6 Address - 128 bits
53
Private IP ranges
Class A = 10.x.x.x
Class B = 172.16.0.0 - 172.31.255.255
Class C = 192.168.x.x
54
DHCP Discover
A message sent from a DHCP client to a DHCP server to request an IP address. Step 1 in the DHCP handshake.
55
DHCP Offer
A message sent from a DHCP server to a DHCP client to tell the client what IP and subnet mask will be given to the client. Step 2 in the DHCP handshake.
56
DHCP Request
The acceptance message to a DHCP Server from a DHCP client responding to a DHCP Offer. Step 3 in the DHCP handshake.
57
OSI Layer 4
Transport - Segments - Communication and message delivery. TCP/UDP
58
OSI Layer 5
Session - Data - Watches sessions and downloads, manages connections.
59
OSI Layer 6
Presentation - Data - Translation, Conversion, Compression, Encryption; (File extensions)
60
OSI Layer 7
Application - Data - HTTP, HTTPS, FTP, DNS, TFTP, SNMP, SMTP
61
TCP Segment Header
Source Port
Port used by the sender
62
TCP Segment Header
Destination Port
Port used by the receiver
63
TCP Segment Header
Sequence Number
byte value sent so far in a TCP flow
64
TCP Segment Header
Flags
SYN (Synchronize)
Used to initiate a connection. It synchronizes sequence numbers between the sender and receiver.
65
TCP Segment Header
Flags
FIN (Finish)
Indicates that the sender has finished sending data and wants to terminate the connection.
66
TCP Segment Header
Window Size
How many packets that can be sent before requesting another ACK from a receiver
67
TCP Segment Header
Checksum
A value generated by the sender. The receiver generates a value using the same calculation, if they match, the segment is error free.
68
TCP Segment Header
Urgent Pointer
Specifies which part of the data is urgent and needs to be processed first by the receiver.
69
TCP Segment Header
Options
Used to specify various options for the packet, such as maximum window size or quick-starting a connection.
70
UDP Segment Header
Source Port
Port used by the sender
71
Half duplex
Send or receive, not both at the same time
72
Full duplex
Send and receive at the same time.
73
Multimode fiber optic
Allows multiple modes to propagate. Cheaper than single mode but not as fast and has shorter distance maximum. Max distance is 550M
74
Singlemode fiber optic
One mode to propagate, very small core diameter, high bandwidth and very long distance, but more expensive than Multimode. Max distance is 100KM.
75
Most common connector types for fiber
LC (Lucent Connector)
SC (Standard Connector)
ST (Straight Tip)
76
Collision domains
A domain within a network that encapsulates all devices that can communicate with a layer one protocol. Switches separate Collision domains.
77
Broadcast domains
A domain within a network that encapsulates all devices that can receive a broadcast message from any other device within that domain. Routers separate broadcast domains.
78
Process switching
Every packet is analyzed by the router's CPU.
79
Fast Switching
A router's CPU checks the first packet of a flow and applies its decision to the rest of the flow
80
Cisco Express Forwarding (CEF)
Works similar to an ARP table, caches switching and keeps it within a table
81
Slash Notation
a subnet mask notation that uses the amount of bits to refer to the subnet mask.
82
OSPF Backbone
Area 0
83
OSPF hello and default settings/multicast IP
A message sent from a router using OSPF to a neighbor to find if it is up or down. Default setting has hello messages sent every 10 seconds with a dead timer at 40 seconds. Uses multicast IP 224.0.0.5.
84
OSPF Router ID (RID)
OSPF identification method that assigns an ID to a router based on the highest IP address in a router's interfaces. Logical (Virtual) interfaces take precedence over other interfaces.
85
OSPF Cost
The Metric used in OSPF that takes Reference Bandwidth and divides it by interface bandwidth. Reference Bandwidth is set manually, default is 100Mbps. Rounds up to the nearest whole number.
86
Command:
wan mode
Decide what interface type a router should use for its WAN connection.
87
Command:
interface (interface)
Change from Global Configuration Mode to Interface Configuration Mode for a specific interface. Interface can be a physical or logical (virtual) interface.
88
Command:
(config-interface)
ip address (IP) (Subnet Mask)
Assign an IP address to the selected interface
89
Command:
(config-interface)
shutdown
Disable the selected interface
90
Command:
(config-interface)
ip ospf passive-interface
Prevent the interface from forming a neighbor and exchanging routing information
91
Command:
(config-interface)
ip ospf hello-interval (seconds)
modify how many seconds between hello intervals.
92
Command:
(config-interface)
ip ospf dead-interval (seconds)
modify how many seconds until an OSPF interface decides a device is down.
93
Command:
line console/aux/vty (start_line) (end_line)
Used to enter the configuration mode for the CLI for various protocols like the console port, aux port, or virtual (SSH/Telnet) port.
94
Command:
username (name)
Define a username for the device's database.
95
Command:
username (name) privilege (0-15)
Set the privilege level for a username. 15 is admin level.
96
Command:
username (name) password/secret (password)
Require and define a password to login to the CLI using this username. Hashed if secret is used.
97
Command:
crypto key generate rsa
Makes a device generate an RSA key. Used to enable SSH and other secure protocols.
98
Command:
copy running-config startup-config
Saves the current configuration of the device. Synonomous with write memory
99
Command:
cdp run
enable CDP. can be ran globally or per-interface
100
Command:
clear cdp table
Wipe the cached CDP table
101
Command:
clock set (time)
configure the current time
102
Command:
show mac-address-table
Shows a list of all discovered MAC addresses on a switch.
103
Command:
show arp
Shows a list of the cached ARP entries within a router or switch.
104
Command:
show running-config
Show the current configuration of the device stored in RAM
105
Command:
show startup-config
Show the saved configuration of the device stored in NVRAM
106
Command:
show interfaces (interface)
show the readout of a specific interface
107
Command:
show cdp
Show the current CDP settings
108
Command:
show cdp neighbors (detail)
show connected cisco devices
109
Command:
show version
gives information on the IOS version as well as other device information.
110
Command:
show ip ospf database
Shows the entirety of the OSPF database
111
Command:
debug ip ospf hello
Show the send/receive OSPF hello messages within a router
112
Command:
debug ip ospf events
Show debug messages for OSPF events
113
Command:
debug ip ospf adjacency
Show debug messages for OSPF adjacency
114
Command:
undebug all
Turn off all debug messages
115
NIC
Network Interface Card - A computer part that usually has an RJ45 port to connect to a networking device.
116
PAN
Personal Area Network - A network between personal devices, such as a mobile phone and a pair of earphones.
117
LAN
Local Area Network - Two or more devices within an isolated network separate from a WAN.
118
TCP
Transmission Control Protocol - Reliable, Connection-oriented reliable stream oriented packet protocol with a 20byte header. - Used with HTTP, SSH, Telnet, ...
119
UDP
User Datagram Protocol - Unreliable, Connectionless, no-confirmation packet protocol with an 8byte header. - Used with VOIP, Video, TFTP, SNMP, DNS, ...
120
TCP SYN
Synchronize - In TCP, A device sends a packet to another device asking to synchronize
121
TCP SYN/ACK
Synchronize/Acknowledgment - In TCP, a device that received a SYN replies with a SYN/ACK to acknowledge and ask for an acknowledgment back.
122
TCP ACK
Acknowledgment - In TCP, a device that sent a SYN and received a SYN/ACK replies with an ACK acknowledging the session has been created.
123
MAC
Media Access Control - sublayer of layer 2. Works alongside LLC
124
LLC
Logical Link Control - sublayer of layer 2. Works alongside MAC.
125
ARP
Address Resolution Protocol - Translates IP addresses into MAC addresses
126
OSPF
Open Shortest Path First - Dynamic Routing Protocol, uses cost as a metric. Uses Areas to separate a network. Updates the route only when a trigger occurs. Supports VLSM and authentication. Automatically prevents loops. CPU intensive and hard to manage/implement.
127
BGP
Border Gateway Protocol - Dynamic Routing Protocol, uses _ as a metric
128
DR/BDR
Designated Router/Backup Designated Router - OSPF election process that declares a router designated. The Designated Router is decided by priority, which is set manually, or if there is a tie, the highest Router ID wins. Uses Multicast IP 224.0.0.6 to declare a DR/BDR
129
Network
Two or more devices that a linked together
130
Hub
A layer one device that connects devices in a LAN and broadcasts all information sent to it to all connected devices.
131
Switch
A layer two device that connects devices in a LAN and differentiates those devices using MAC addresses.
132
Router
A layer three device that connects two or more LANs and routes messages.
133
Firewall
A device dedicated to network security.
134
DHCP Ack
The message of acknowledgment from a DHCP Server to a DHCP client after the server receives the DHCP request message from a client. Step 4 (final) in the DHCP handshake.
135
Unicast
A message sent from one device to another device.
136
Multicast
A message sent from one device to multiple devices.
137
Broadcast
A message sent from one device to all devices.
138
3 modes for Cisco IOS
User Exec mode - Basic mode, no root access
Privileged mode - Root access to all commands
Global Configuration Mode - Root access and in process of applying changes to the configuration
139
OSI Layer 1
Physical Layer - Literal bits of data - Electrical signals or light through cables or waves through WiFi, Bluetooth, etc.
140
OSI Layer 2
Data Link - Frames - LAN devices that communicate using MAC and LLC
141
OSI Layer 3
Network - Packets - Routers and Routing; IP addresses. Decides how and where to send information.
142
TCP Segment Header
Acknowledgment Number
The expected next sequence number in a TCP flow
143
TCP Segment Header
Data Offset
A value of 5-15, explaining how big the packet header is in bytes divided by 4
144
TCP Segment Header
Reserved
Unusued data for future usage
145
TCP Segment Header
Flags
8 options that can be used to indicate special information being sent.
146
TCP Segment Header
Flags
URG (Urgent)
Indicates that the Urgent Pointer field is significant. It is used to prioritize certain data.
147
TCP Segment Header
Flags
ACK (Acknowledgment)
Indicates that the Acknowledgment field is significant. It is used to acknowledge the receipt of data.
148
TCP Segment Header
Flags
PSH (Push)
Instructs the receiver to pass the data to the application immediately.
149
TCP Segment Header
Flags
RST (Reset)
Resets the connection. It is used to abort a connection in case of errors or unexpected conditions.
150
UDP Segment Header
Destination Port
Port used by the receiver
151
UDP Segment Header
Length
The length of the segment.
152
UDP Segment Header
Checksum
A value generated by the sender. The receiver generates a value using the same calculation, if they match, the segment is error free.
153
TCP Session 3 way handshake
SYN, SYN/ACK, ACK
154
Common ports
20/21 - FTP, 22 - SSH, 23 - Telnet,
25 - SMTP, 53 - DNS, 80 - HTTP,
110 - POP3, 443 - HTTPS, 3389 - RDP
155
MAC Address
A unique designation to a NIC given by the NIC manufacturer. The first 3 bytes are manufacturer identifications (OUI), and the last 3 are unique to the device.
156
Frame
A message sent at layer two
157
Port speed standards
Fast Ethernet (100Mbps), Gigabit Ethernet (1Gbps), 10-Gigabit Ethernet (10Gbps)
158
TCP/IP model vs OSI model
TCP/IP model has 4 layers, Application, Transport, Internet, Network Interface.
Application = layers 5, 6, 7 in OSI. Transport = layer 4,
Internet = Layer 3,
Network Interface = Layer 2 and 1.
159
Encapsulation
Encapsulation is done using the TCP/IP model and all 4 layers are used. Data at layer 4 is given TCP/UDP header and data info at layer 3 then given an IP header in a packet at layer 2 and then given frame header and trailer at layer 1.
160
Static route
Admin defined route that can only be changed by configuring the router manually.
161
Dynamic Route and main dynamic routing protocols
Router defined route that was created by a router communicating with another router. Main protocols are RIP, EIGRP, OSPF, and BGP.
162
Routing Table
A table that all routers have to define where to route a packet given to it.
163
Routing Metric
A form of measurement used to tell how "good" a route is decided by the protocol that added it.
164
Administrative Distance
A value given to a route based on how it was added to the routing table. Directly connected = 0, Static = 1, BGP external = 20, EIGRP = 90, OSPF = 110, RIP = 120, BGP internal = 200, Unknown = 255
165
Default route
Gateway of Last Resort
Default Gateway
A route that all traffic sent from a router that is not processed goes through.
166
OSPF Wildcard mask
OSPF network mask. Similar but opposite to a subnet mask, for instance a subnet mask of 255.255.255.0 becomes an OSPF wildcard mask of 0.0.0.255.
167
Name System lookup, queries the DNS server to return an IP
Command:
nslookup
168
Change from User Exec mode to Privileged mode
Command:
enable
169
Change from Privileged mode to global Configuration mode
Command:
configure terminal
170
Exit the current mode to the previous one, or log out if at the beginning mode.
Command:
exit
171
Allows you to run a non-config command while in config mode.
Command:
do
172
Undoes a configuration
Command:
no
173
Change the hostname of the Cisco device
Command:
hostname (name)
174
Change the domain name of the Cisco device
Command:
ip domain-name (name)
175
Make it so a CLI does not interrupt a command while it is being typed if a debug message is received
Command:
logging synchronous
176
Require and define a password to access the selected line
Command:
(config-line)
password
177
Require and define a password that is hashed to access the selected line.
Command:
(config-line)
secret
178
Use the local database to login to this line instead of a defined password/database for this line specifically.
Command:
(config-line)
login local
179
Selects which protocols are allowed to access this line.
Command:
(config-line)
transport input (input)
180
Require and define a password to enter Privileged mode.
Command:
enable password
181
Require and define a password that is hashed to enter Privileged mode.
Command:
enable secret
182
Encrypts new passwords within the device.
Command:
service password-encryption
183
create or configure a timezone to be used on the device
Command:
clock timezone (timezone name) (hours from UTC)
184
adds a static entry to a device's routing table.
Command:
ip route (destination) (mask) (next hop/exit interface)
185
Enter the router configuration mode for a specific protocol
Command:
router (protocol) (number)
186
configure the OSPF settings on a router
Command:
router ospf (number)
187
configure the reference bandwidth for OSPF.
Command:
auto-cost reference-bandwidth (number)
188
Enables OSPF on all interfaces within the defined network and designates its area number.
Command:
network (network IP) (Wildcard mask) area (area number)
189
Shows all network interfaces, their IP addresses, if they are OK, what method they use to connect, their status, and their protocol.
Command:
show ip interface brief
190
Shows a routing table in a router
Command:
show ip route
191
Gives information of the hardware name, revision, product ID, serial number, and others.
Command:
show inventory
192
outputs a lot of information on the router used for Cisco tech support.
Command:
show tech-support
193
outputs the line status and protocols for all interfaces
Command:
show protocols
194
outputs the IP protocols currently running on the device.
Command:
show ip protocols
195
Return the current time.
Command:
show clock
196
Show files saved on flash, which will include the operating system.
Command:
show flash
197
Show the routing table currently in use by the device
Command:
show ip route
198
Shows the OSPF table of neighbors within a router.
Command:
show ip ospf neighbor
199
Wide Area Network - A network that consists of more than one LAN
WAN
200
Wireless LAN - A LAN that is connected via Wireless means, such as Wi-Fi
WLAN
201
Small Office/Home Office - A SOHO device would be a device that functions as many networking devices.
SOHO
202
Internet Protocol
IP
203
Dynamic Host Configuration Protocol - A protocol used to assign IP addresses to clients from a server.
DHCP
204
Domain Name System - Translates names to IP addresses
DNS
205
Internetwork Operating System - Cisco operating system for Cisco network devices.
Cisco IOS
206
Open System Interconnection - 7 Layer model used as a standard of describing levels of networking.
OSI Model
207
Power over Ethernet - Allows Electrical Current over an Ethernet cable. Two standards, IEEE 802.3af (16.8 Watts) and 802.3at (PoE+, 16.8 Watts)
PoE
208
Small Form-factor Pluggable - Transceivers used to connect network devices to different types of cables, usually fiber.
SFP
209
Carrier Sense Multiple access with Collision Avoidance - Check if it is okay to send data, if it is, send it. Used for wireless networks.
CSMA/CA
210
Carrier Sense Multiple access with Collision Detection - Send data and detect if any collisions occur. Full duplex and switches make this obsolete.
CSMA/CD
211
Cisco Discovery Protocol - Cisco proprietary discovery protocol used to find directly linked devices.
CDP
212
Link Layer Discovery Protocol - Standard protocol used to find directly linked devices.
LLDP
213
Routing Information Protocol - Dynamic Routing Protocol, uses a count of hops on a network path for the metric.
RIP
214
Enhanced Interior Gateway Routing Protocol - Dynamic Routing Protocol, uses a calculation for a metric. Cisco Proprietary. The calculation is based on Bandwidth, Load, Delay, and Reliability.
EIGRP
215
A device that bridges connection between wireless and wired networks.
Access point
216
A device that centralizes operations for admin tasks.
Controller
217
A device that functions as many devices, such as a firewall, router, Access Point, and switch.
SOHO Router
218
An address used to identify a network device, unique within a network. IPv4 Address - 32 bits (4 octet/byte), IPv6 Address - 128 bits
IP Address
219
Class A = 10.x.x.x
Class B = 172.16.x.x - 172.31.x.x
Class C = 192.168.x.x
Private IP ranges
220
A message sent from a DHCP client to a DHCP server to request an IP address. Step 1 in the DHCP handshake.
DHCP Discover
221
A message sent from a DHCP server to a DHCP client to tell the client what IP and subnet mask will be given to the client. Step 2 in the DHCP handshake.
DHCP Offer
222
The acceptance message to a DHCP Server from a DHCP client responding to a DHCP Offer. Step 3 in the DHCP handshake.
DHCP Request
223
Transport - Segments - Communication and message delivery. TCP/UDP
OSI Layer 4
224
Session - Data - Watches sessions and downloads, manages connections.
OSI Layer 5
225
Presentation - Data - Translation, Conversion, Compression, Encryption; (File extensions)
OSI Layer 6
226
Application - Data - HTTP, HTTPS, FTP, DNS, TFTP, SNMP, SMTP
OSI Layer 7
227
Port used by the sender
TCP Segment Header
Source Port
228
Port used by the receiver
TCP Segment Header
Destination Port
229
byte value sent so far in a TCP flow
TCP Segment Header
Sequence Number
230
Used to initiate a connection. It synchronizes sequence numbers between the sender and receiver.
TCP Segment Header
Flags
SYN (Synchronize)
231
Indicates that the sender has finished sending data and wants to terminate the connection.
TCP Segment Header
Flags
FIN (Finish)
232
How many packets that can be sent before requesting another ACK from a receiver
TCP Segment Header
Window Size
233
A value generated by the sender. The receiver generates a value using the same calculation, if they match, the segment is error free.
TCP Segment Header
Checksum
234
Specifies which part of the data is urgent and needs to be processed first by the receiver.
TCP Segment Header
Urgent Pointer
235
Used to specify various options for the packet, such as maximum window size or quick-starting a connection.
TCP Segment Header
Options
236
Port used by the sender
UDP Segment Header
Source Port
237
setting for sending and receiving data.
Duplex
238
Send or receive, not both at the same time
Half duplex
239
Send and receive at the same time.
Full duplex
240
Allows multiple modes to propagate. Cheaper than single mode but not as fast and has shorter distance maximum. Max distance is 550M
Multimode fiber optic
241
One mode to propagate, very small core diameter, high bandwidth and very long distance, but more expensive than Multimode. Max distance is 100KM.
Singlemode fiber optic
242
LC, SC, ST
Most common connector types for fiber
243
A domain within a network that encapsulates all devices that can communicate with a layer one protocol. Switches separate Collision domains.
Collision domains
244
A domain within a network that encapsulates all devices that can receive a broadcast message from any other device within that domain. Routers separate broadcast domains.
Broadcast domains
245
Every packet is analyzed by the router's CPU.
Process switching
246
A router's CPU checks the first packet of a flow and applies its decision to the rest of the flow
Fast Switching
247
Works similar to an ARP table, caches switching and keeps it within a table
Cisco Express Forwarding (CEF)
248
a subnet mask notation that uses the amount of bits to refer to the subnet mask.
Slash Notation
249
Area 0
OSPF Backbone
250
A message sent from a router using OSPF to a neighbor to find if it is up or down. Default setting has hello messages sent every 10 seconds with a dead timer at 40 seconds. Uses multicast IP 224.0.0.5.
OSPF hello
251
OSPF identification method that assigns an ID to a router based on the highest IP address in a router's interfaces. Logical (Virtual) interfaces take precedence over other interfaces.
OSPF Router ID (RID)
252
The Metric used in OSPF that takes Reference Bandwidth and divides it by interface bandwidth. Reference Bandwidth is set manually, default is 100Mbps. Rounds up to the nearest whole number.
OSPF Cost
253
Decide what interface type a router should use for its WAN connection.
Command:
wan mode
254
Change from Global Configuration Mode to Interface Configuration Mode for a specific interface. Interface can be a physical or logical (virtual) interface.
Command:
interface (interface)
255
Assign an IP address to the selected interface
Command:
ip address (IP) (Subnet Mask)
256
Disable the selected interface
Command:
shutdown
257
Prevent the interface from forming a neighbor and exchanging routing information
Command:
ip ospf passive-interface
258
modify how many seconds between hello intervals.
Command:
ip ospf hello-interval (seconds)
259
modify how many seconds until an OSPF interface decides a device is down.
Command:
ip ospf dead-interval (seconds)
260
Used to select the CLI for various protocols like the console port, aux port, or virtual (SSH/Telnet) port.
Command:
line console/aux/vty (start_line) (end_line)
261
Define a username for the device's database.
Command:
username (name)
262
Set the privilege level for a username. 15 is admin level.
Command:
username (name) privilege (0-15)
263
Require and define a password to login to the CLI using this username. Hashed if secret is used.
Command:
username (name) password/secret (password)
264
Makes a device generate an RSA key. Used to enable SSH and other secure protocols.
Command:
crypto key generate rsa
265
Saves the current configuration of the device. Synonomous with write memory
Command:
copy running-config startup-config
266
nable CDP. can be ran globally or per-interface
Command:
cdp run
267
Wipe the cached CDP table
Command:
clear cdp table
268
configure the current time
Command:
clock set (time)
269
Shows a list of all discovered MAC addresses on a switch.
Command:
show mac-address-table
270
Shows a list of the cached ARP entries within a router or switch.
Command:
show arp
271
Show the current configuration of the device stored in RAM
Command:
show running-config
272
Show the saved configuration of the device stored in NVRAM
Command:
show startup-config
273
show the readout of a specific interface
Command:
show interfaces (interface)
274
Show the current CDP settings
Command:
show cdp
275
show connected cisco devices
Command:
show cdp neighbors (detail)
276
gives information on the IOS version as well as other device information.
Command:
show version
277
Shows the entirety of the OSPF database
Command:
show ip ospf database
278
Show the send/receive OSPF hello messages within a router
Command:
debug ip ospf hello
279
Show debuf messages for OSPF events
Command:
debug ip ospf events
280
Show debug messages for OSPF adjacency
Command:
debug ip ospf adjacency
281
Turn off all debug messages
Command:
undebug all
282
Network Interface Card - A computer part that usually has an RJ45 port to connect to a networking device.
NIC
283
Personal Area Network - A network between personal devices, such as a mobile phone and a pair of earphones.
PAN
284
Local Area Network - Two or more devices within an isolated network separate from a WAN.
LAN
285
Transmission Control Protocol - Reliable, Connection-oriented reliable stream oriented packet protocol with a 20byte header. - Used with HTTP, SSH, Telnet, ...
TCP
286
User Datagram Protocol - Unreliable, Connectionless, no-confirmation packet protocol with an 8byte header. - Used with VOIP, Video, TFTP, SNMP, DNS, ...
UDP
287
Synchronize - In TCP, A device sends a packet to another device asking to synchronize
TCP SYN
288
Synchronize/Acknowledgment - In TCP, a device that received a SYN replies with a SYN/ACK to acknowledge and ask for an acknowledgment back.
TCP SYN/ACK
289
Acknowledgment - In TCP, a device that sent a SYN and received a SYN/ACK replies with an ACK acknowledging the session has been created.
TCP ACK
290
Media Access Control - sublayer of layer 2. Works alongside LLC
MAC
291
Logical Link Control - sublayer of layer 2. Works alongside MAC.
LLC
292
Address Resolution Protocol - Translates IP addresses into MAC addresses
ARP
293
Open Shortest Path First - Dynamic Routing Protocol, uses cost as a metric. Uses Areas to separate a network. Updates the route only when a trigger occurs. Supports VLSM and authentication. Automatically prevents loops. CPU intensive and hard to manage/implement.
OSPF
294
Border Gateway Protocol - Dynamic Routing Protocol, uses _ as a metric
BGP
295
Designated Router/Backup Designated Router - OSPF election process that declares a router designated. The Designated Router is decided by priority, which is set manually, or if there is a tie, the highest Router ID wins. Uses Multicast IP 224.0.0.6 to declare a DR/BDR
DR/BDR
296
Two or more devices that a linked together
Network
297
A layer one device that connects devices in a LAN and broadcasts all information sent to it to all connected devices.
Hub
298
A layer two device that connects devices in a LAN and differentiates those devices using MAC addresses.
Switch
299
A layer three device that connects two or more LANs and routes messages.
Router
300
A device dedicated to network security.
Firewall
301
The message of acknowledgment from a DHCP Server to a DHCP client after the server receives the DHCP request message from a client. Step 4 (final) in the DHCP handshake.
DHCP Ack
302
A message sent from one device to another device.
Unicast
303
A message sent from one device to multiple devices.
Multicast
304
A message sent from one device to all devices.
Broadcast
305
User Exec mode - Basic mode, no root access
Privileged mode - Root access to all commands
Global Configuration Mode - Root access and in process of applying changes to the configuration
3 modes for Cisco IOS
306
Physical Layer - Literal bits of data - Electrical signals or light through cables or waves through WiFi, Bluetooth, etc.
OSI Layer 1
307
Data Link - Frames - LAN devices that communicate using MAC and LLC
OSI Layer 2
308
Network - Packets - Routers and Routing; IP addresses. Decides how and where to send information.
OSI Layer 3
309
The expected next sequence number in a TCP flow
TCP Segment Header
Acknowledgment Number
310
A value of 5-15, explaining how big the packet header is in bytes divided by 4
TCP Segment Header
Data Offset
311
Unusued data for future usage
TCP Segment Header
Reserved
312
8 options that can be used to indicate special information being sent.
TCP Segment Header
Flags
313
Indicates that the Urgent Pointer field is significant. It is used to prioritize certain data.
TCP Segment Header
Flags
URG (Urgent)
314
Indicates that the Acknowledgment field is significant. It is used to acknowledge the receipt of data.
TCP Segment Header
Flags
ACK (Acknowledgment)
315
Instructs the receiver to pass the data to the application immediately.
TCP Segment Header
Flags
PSH (Push)
316
Resets the connection. It is used to abort a connection in case of errors or unexpected conditions.
TCP Segment Header
Flags
RST (Reset)
317
Port used by the receiver
UDP Segment Header
Destination Port
318
The length of the segment.
UDP Segment Header
Length
319
A value generated by the sender. The receiver generates a value using the same calculation, if they match, the segment is error free.
UDP Segment Header
Checksum
320
SYN, SYN/ACK, ACK
TCP Session 3 way handshake
321
20/21 - FTP, 23 - Telnet,
25 - SMTP, 53 - DNS, 80 - HTTP,
110 - POP3, 443 - HTTPS, 3389 - RDP
Common ports
322
A unique designation to a NIC given by the NIC manufacturer. The first 3 bytes are manufacturer identifications (OUI), and the last 3 are unique to the device.
MAC Address
323
A message sent at layer two
Frame
324
Fast Ethernet (100Mbps), Gigabit Ethernet (1Gbps), 10-Gigabit Ethernet (10Gbps)
Port speed standards
325
TCP/IP model has 4 layers, Application, Transport, Internet, Network Interface.
Application = layers 5, 6, 7 in OSI. Transport = layer 4,
Internet = Layer 3,
Network Interface = Layer 2 and 1.
TCP/IP model vs OSI model
326
Encapsulation is done using the TCP/IP model and all 4 layers are used. Data at layer 4 is given TCP/UDP header and data info at layer 3 then given an IP header in a packet at layer 2 and then given frame header and trailer at layer 1.
Encapsulation
327
Admin defined route that can only be changed by configuring the router manually.
Static route
328
Router defined route that was created by a router communicating with another router. Main protocols are RIP, EIGRP, OSPF, and BGP.
Dynamic Route
329
A table that all routers have to define where to route a packet given to it.
Routing Table
330
A form of measurement used to tell how "good" a route is decided by the protocol that added it.
Routing Metric
331
A value given to a route based on how it was added to the routing table. Directly connected = 0, Static = 1, BGP external = 20, EIGRP = 90, OSPF = 110, RIP = 120, BGP internal = 200, Unknown = 255
Administrative Distance
332
A route that all traffic sent from a router that is not processed goes through.
Default route
Gateway of Last Resort
Default Gateway
333
OSPF network mask. Similar but opposite to a subnet mask, for instance a subnet mask of 255.255.255.0 becomes an OSPF wildcard mask of 0.0.0.255.
OSPF Wildcard mask
