ICND1 Flashcards
OSI Layers
Physical, Data Link, Network, Transport, Session, Presentation, Application
What is the data link layer address for Ethernet
MAC
What are the non-overlapping channels in the 2.4 Ghz frequency for wireless access points.
1, 6, and 11
Basic function of IPS
Learn normal behavior of network and block or warn when an abnormality is observed.
IOS Configuration, interface mode, ‘ntp broadcast’
Sends NTP broadcasts
What do the following port light colors indicate on a Cisco switch?
no light green blinking green alternating green-amber amber blinking amber
no light - no link, or port is admin down.
green - link present
blinking green - activity (normal operation)
alternating - link fault: errors such as excessive collisions, CRC, alignment, and jabber.
amber - port blocked by STP while listening or learning
blinking amber - port is in STP blocking state
What conditions might cause a switch port status light to remain unlit?
admin down or link down.
Link down may be due to encapsulation or other layer 2 protocol mismatch, a bad or incorrect cable, or a lack of signal.
For numbered ACLs what are the number ranges for standard and extended IP ACLs
standard: 1-99 and 1300-1999
extended: 100-199 and 2000-2699
Describe the OSI Application Layer
This layer interacts directly with applications.
These services include FTP, SMTP, HTTP, DHCP, et al.
Describe the OSI Presentation Layer
This is not always used. It handles translation, compression, and encryption. Translation changes the data to be understood by different types of computers such as changing LF to CRLF in an ASCII FTP transfer.
Describe the OSI Session Layer
Creates, manages, and terminates sessions between communicating nodes. These are APIs such as NetBIOS, TCP/IP Sockets aka Python SocketIO, and RPC.
Describe the OSI Transport layer
It has two main parts. One is keeping track of what data comes from what application and combining that data into a single flow for use by the lower layers. The receiving device reverses this operation. Dividing the data into segments ready for layer 2 and 3 encapsulation is also done here.
Part 2 TCP/UDP - providing either connection-oriented (TCP) or connectionless (UDP) services. Connection-oriented services include flow control, keeping packets in order, recovering from lost transmissions or errors. Connectionless services do almost nothing apart from keeping track of which application the traffic belongs to. They are called best-effort because if the data is lost there is no attempt to recover it.
Describe the OSI Network Layer
This layer handles logical addressing, routing, datagram encapsulation, fragmentation and reassembly, and error handling and diagnostics. Error handling and diagnostics doesn’t include data recovery. The most common example of this is a routing protocol using a ‘hello’ protocol to verify the link is up.
Describe the OSI Data Link Layer
This includes logical link control, media access control, data framing, local addressing, and error detection and handling. Common error detection includes the checksum on Ethernet frames.
Describe the OSI Physical Layer
This includes hardware specifications, encoding and signaling, and data transmission and reception.
Layer 1 devices are CSU/DSU, transceivers, and repeaters that take bit streams and convert or repeat them without regard to the structure at the other layers.
What are the 7 layers of the OSI model
Physical, Data Link, Network, Transport, Session, Presentation, and Application
What are the major letters used in the ‘show ip route’ command and their associated protocol
C - connected S - static R - RIP B -BGP D - EIGRP EX - EIGRP external I - IGRP (deprecated) O - OSPF i - IS-IS o - ODR
Which protocol is used by Ethernet to control transmission over a shared medium. Which similar protocol is used by WiFi?
CSMA/CD for Ethernet
(Carrier Sense Multiple Access / Collision Detection)
CSMA/CA for WiFi (Carrier Sense Multiple Access / Collision Avoidance)
Answer one to \_\_\_\_ for the following: Unicast Multicast Broadcast Anycast
Unicast: One to One
Multicast: One to Many
Broadcast: One to All
Anycast: One to Any
Which method do network devices use to translate a name to an IP address
DNS
What is the RFC number for private IPv4 address space?
RFC 1918
List the RFC 1918 address ranges
- 0.0.0 - 10.255.255.255
- 16.0.0 - 172.31.255.255
- 168.0.0 - 192.168.255.255
List differences between UDP and TCP
TCP deliveries all packets in order
UDP delivers whatever packets arrive.
TCP has higher overhead.
UDP is better for real-time applications like VoIP
TCP is connection-oriented
UDP is connectionless
TCP is slower
TCP does error checknig and error recovery
UDP does error checking but discards and does not recover
TCP has a handshake UDP does not
What is TCP sliding window?
The adjustment in quantity of data sent before the sender receives an acknowledgement
What are the 3 steps in a TCP 3-way handshake.
SYN (initiator)
SYN-ACK (responder)
ACK (initiator)
List the differences between the TCP/IP reference model and the OSI reference model. (Layer names will be covered on other slides)
OSI is protocol independent
OSI is a reference model and TCP/IP is an implementation
OSI model has 7 layers and the TCP/IP model has 4 layers.
What OSI layer(s) provider similar functionality to the TCP/IP Application layer?
Application, Presentation, and Session
What TCP/IP model layer provides the functionality of the OSI Presentation layer?
Application
What TCP/IP model layer provides the functionality of the OSI Session layer?
Application
What TCP/IP model layer provides the functionality of the OSI Transport layer?
Transport
What TCP/IP model layer provides the functionality described by the OSI Network layer.
Internet layer
What TCP/IP model layer provides the functionality described by the OSI data-link layer?
Network Access layer
What TCP/IP model layer provides the functionality described by the OSI physical layer?
Network Access layer
What OSI layer(s) describe the functionality of the TCP/IP Transport layer?
Transport layer
What OSI layer(s) describe the functionality of the TCP/IP Internet layer.
Network layer
What OSI layer(s) describe the functionality of the TCP/IP Network Access layer
Data Link layer and Physical layer
List the main IOS Command modes
User EXEC Privileged EXEC Global configuration Interface configuration Subinterface configuration ROM monitor
List configuration required for SSH access
line vty 0 4 login local transport input ssh/all username xxx secret xxx hostname router ip domain-name example.com crypto key generate rsa
Command to view table of interface mac address mapping
show mac address-table
Command to view directly connected Cisco devices
show cdp neighbors
Commands to enable lldp globally, disable it on an interface, and view discovered neighbors.
global: lldp run
interface: no lldp transmit
EXEC: show lldp neighbors
What is LLDP an acronym for?
Link Layer Discovery Protocol
Describe the three possible response types for switchport port-security
protect: block traffic from any MAC addresses beyond the number allowed
restrict: same as protect but will log violations
shutdown: will err-disable the port if the number of allowed MAC addresses are exceeded
Command for a sticky mac in port security
switchport port-security mac-address sticky