VLANs and Trunk

Question 1

What is a VLAN?

Answer 1

VLAN is a Layer 2 feature that represents a broadcast domain, enabling network
administrators to create several virtual LANs on a single switch.

Question 2

What are the benefits of VLANs?

Answer 2

Security, Improvement, and Simplicity

Question 3

What is a VLAN ID?

Answer 3

A unique ID identifies a VLAN in the network.

Question 4

What is the Default VLAN?

Answer 4

VLANs 1 and 1002-1005 are reserved and added automatically during
device installation. These IDs cannot be removed

Question 5

What is the Data VLAN?

Answer 5

VLANs 2-1001 are commonly used by users for data exchanges. Their main
function is to tag data traffic with an identifier.

Question 6

What is the Voice VLAN?

Answer 6

This VLAN is designed for VoIP (Voice over IP) networks.

Question 7

What is the Management VLAN?

Answer 7

Interface VLAN 1 is a management VLAN that uses a Layer 3 interface called SVI. The management VLAN is also used for remote connection via protocols such as Telnet and SSH.

Question 8

What is Native VLAN?

Answer 8

Native VLANs forward untagged traffic, such as DTP and CDP.

Question 9

What are the two Switchport Modes?

Answer 9

the two modes are Access or Trunk

Question 10

What is Access mode?

Answer 10

The Access port is used when connecting end devices. example, when
connecting a PC to a switch

Question 11

What is Trunk mode?

Answer 11

Trunk ports carry traffic for different VLANs and devices. The port sets unique
identifier tags on the frame, using either the 802.1Q or ISL encapsulation protocol

Question 12

When should you enable access mode?

Answer 12

Before assigning it to a VLAN

Question 13

What are the two mist common trunking protocols?

Answer 13

ISL (Inter-Switch Link) developed by CISCO and 802.1q was developed by IEEE. It is the default protocol in most switches today.

Question 14

What is DTP?

Answer 14

DTP is a protocol developed by Cisco to create Trunk links automatically. It operates by default on all Cisco switches but can be turned off for security purposes.
DTP automatically “negotiates” for packets between interconnected switches.

Question 15

What are the two DTP modes?

Answer 15

Dynamic Auto - This mode, which is the default for each port, is passive and does not
negotiate.
Dynamic Desirable - This mode allows DTP negotiation packets to be sent to the switch
on the other side of the connection

Question 16

What is the default Native VLAN?

Answer 16

VLAN 1

Question 17

What is Router-On-A-Stick?

Answer 17

Requires only a single physical connection between the switch and the router, avoiding the need for additional components and costs.

Question 18

What are the two type of Sub-Interfaces?

Answer 18

Multiple IP addresses (multiple interfaces and addresses) and Logical interfaces (unique ip address)

Question 19

What is CDP?

Answer 19

Cisco Discovery Protocol (CDP) is a Layer 2 Cisco proprietary protocol enabled by
default on all Cisco devices. Its purpose is similar to that of NDP.
CDP can be disabled on specific devices or interfaces, for security purposes

Question 20

3 CDP Attributes?

Answer 20

Eavesdropping, Information Gathering and Advertisements

Question 21

What is CDP Eavesdropping?

Answer 21

Since CDP does not encrypt transmitted data, it is vulnerable to
reconnaissance type attacks (such as sniffing) that, for example, allow an attacker to
map the victim’s network.

Question 22

What is CDP Information Gathering?

Answer 22

CDP gathers information on the local device and periodically sends it to all directly connected devices.

Question 23

What is CDP Advertisements?

Answer 23

• CDP advertisements are special packets that reveal device details to
  neighbors also running CDP.

Question 24

What is CDP Mismatch Error Detection?

Answer 24

Feature that can detect a protocol-connection mismatch. When such a mismatch is detected, CDP notifies the network administrator by recording the incident in a log.
Examples of mismatch types include:
* Native VLAN mismatch
* Duplex mismatch

Question 25

When intervals are CDP Advertisement sent?

Answer 25

Advertisement packets are sent every 60 seconds to all directly connected devices.
When a device does not receive Hello packets from its neighbor for 180 seconds, it will
consider the neighbor “dead,” and remove it from its CDP neighbor table.

Question 26

What is LLDP (Link Layer Discovery Protocol)?

Answer 26

LLDP (Link Layer Discovery Protocol) is a Neighbor Discovery Protocol similar to CDP
that was developed by the IEEE.

Question 27

When intervals are LLDP advertisement packets sent?

Answer 27

They are sent to LLDP neighbors at periodic intervals, which is 60 seconds by default. You can increase or decrease the interval as necessary. The default interval recommended by IEEE is 30 seconds, but any value between 5 and 300 seconds
can be specified. When a device does not receive Hello packets from its neighbor for 120 seconds, it will consider the neighbor “dead”, and remove it from its LLDP neighbor table.

Question 28

What is NTP?

Answer 28

NTP (Network Time Protocol) is responsible for the synchronization of all clocks in
devices on the network. NTP is a client-server protocol. All clients must be configured with the NTP server’s IP address, so that they will all have the same date and time.