Flashcards in Vol 1 Part 2: Implementing Ethernet LANs Deck (40)
All interfaces by default reside on which vlan?
VLAN 1, also known as the default VLAN
What is the difference between END and EXIT?
End brings you back to enable mode, exit brings you back up one level in the configuration mode.
What are the 3 things a switch is responsible for performing?
Whether to forward or filter a frame, learning the source MAC address for storage in the CAM table, and forwarding the frame with a layer 2 loop-free environment via the Spanning Tree Protocol (STP).
What does AAA stand for, what is it used for, and what types of services do we use to obtain AAA?
Authentication, authorization, and accounting. It is used for securing credentials for remote access ie. SSH and Telnet. TACACS+ and RADIUS are the most commonly used services for AAA.
What are the 4 types of memory in a cisco switch, and what is stored in each memory?
RAM- stores working memory and running config
Flash- stores the Cisco IOS
ROM- stores the bootstrap program
NVRAM- stores the startup config
Why is Telnet considered undesirable?
It is unsecure due to plain text input
Explain the IEEE rules for auto negotiation, as well as the Cisco rules (hint, there's 2 rules for each!)
IEEE Rule 1: Use the slowest speed supported
IEEE Rule 2: If speed is 10 or 100, use half duplex. Otherwise, full duplex.
Cisco Rule 1: Sense the speed. If speed cannot be sensed, use slowest speed supported.
Cisco Rule 2: Same as IEEE rule 2
Which Cisco switch is the most commonly used today?
The Cisco 2960XR
What commands are used to show the CAM table? (Hint, there are 2, as the second one shows us slightly different information)
Show mac-address table and Show mac-address table dynamic. The first one shows all of the MAC addresses and the ports on the switch, while the second one just shows the addresses the switch has learned on its own (dynamically).
What does the shutdown command do, and what can we learn by examining the status of the interfaces on the switch with respect to the shutdown command?
The shutdown command turns off an interface. If we look a the list of interfaces on the switch and see that an interface is administratively down, then we know that someone shutdown the port manually.
What is Line VTY used for?
Remote access via telnet/SSH
What commands are used in order to configure SSH?
Hostname, IP domain-name, Crypto key generate rsa, Username/secret, Line vty 0 15, Login local
What happens if a switch receives a frame that has a destination MAC address not currently in the CAM table?
The frame is forwarded/flooded out on all ports except the source. The port with the corresponding MAC address responds to the switch with the MAC address, and the switch creates a new entry in the CAM table for that MAC address.
What happens to a frame if there is no entry for it on the MAC table and there is no response received from any interface after the switch has sent a flooded broadcast message?
It will drop the frame
What is a late collision and what does it mean for our network if we are experiencing late collisions?
Late collisions are the collisions that occur after the 64th byte has been transmitted. Ideally, collisions occur before the 64th byte, and if we experience late collisions, then we most likely have a duplex mismatch?
What command is used to encrypt plain text passwords on the switch?
What is the show command used for?
To show all available commands that can be utilized with whatever command is typed in after the word show in the CLI. This is helpful in the event that you forget what command you need to use.
What does it mean if an engineer is bouncing a port?
He is issuing a shutdown command followed by a no shutdown command.
What are the two types of modes when accessing a switch and what are the differences?
User mode and privileged mode (also known as enable mode). User mode allows a user to view limited items and make no changes. Enable mode allows the user to execute admin level commands and view all settings in the switch.
Why is SSH the preferred method for remote access into a switch?
The connection is encrypted.
What on the switch is used to connect devices? Give BOTH names
What 2 commands are used to set up a privileged password for enable mode, and what are the differneces?
enable password and enable secret. Enable password is plain text while enable secret is hashed. Remember! enable secret supersedes enable password.
What is the default MAC Table time, and how can you change it?
300 seconds. Can be changed using the mac address-table agingtime command.
How do you store the running config and start up config in the NVRAM?
By using the command "copy running-config startup config" or "copy run start" for short
What does a switch look at in order to learn new MAC addresses for the CAM table?
The source MAC address of the frame it received.
How do you configure IPv4 on a layer 2 switch?
Interface VLAN 1, ip address, no shutdown, ip default-gateway
What is a runt?
A frame that is less than 64 bytes. REMEMBER! A switch will pad that frame in order to get it up to 64 bytes.
What is the difference between TACACS+ and RADIUS?
TACACS+ is Cisco proprietary and utilizes TCP. Radius is vendor neutral and utilizes UDP.
Why do we need an IPv4 address on a switch, and where do we usually assign this IP address?
To enable management and remote access. It is usually assigned to a VLAN other than the default VLAN.