Network Engineer Interview Questions

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Network Engineer Interview Questions

Network Engineer Interview Questions

What is the name of all OSI Layers?

OSI have 7 Layers

  1. Physical layer
  2. Data Link Layer
  3. Network Layer
  4. Transport Layer
  5. Session Layer
  6. Presentation Layer
  7. Application Layer

What is Switch?

  • Switch is an intelligent device which forwards the traffic i.e. frame based on layer-2 address or MAC-address.
  • If destination MAC-address is found on the MAC-Table then frames are just delivered to appropriate Port.
  • If frames have unknown destination then switch broadcast the frame to all the ports except the port from where it was received.

What is MAC Address?

  • MAC is 48 bits hexadecimal address.
  • Starting 24 bits are called as manufacturer code.
  • MAC address is also called as physical address.
  • MAC-address is multiple access technology used on Ethernet.
  • MAC- address is unique in the word.

What is a MAC- Address Table?

MAC-address Table is the binding of MAC-address learned on the port of the Device (Switch)

What is Public IP and Private IP address?

Public IP Address: A Public IP address is the address that assign to a computing device to allow direct access over the internet. A public IP address is globally unique, and can only be assigned to a unique device over internet.

Private IP Address: Private IP addresses are used in the private network for private communications only.

IP Range

  • Class A: 1.0.0.0 – 126.255.255.255
  • Class B: 128.0.0.0 – 191.255.255.255
  • Class C: 192.0.0.0 – 223.25.255.255
  • Class D: 224.0.0.0 – 239.255.255.255
  • Class E : 240.0.0.0 – 254.255.255.255

(127.0.0.0 is Universal Loopback address)

Private IP Address Range

  • Class A: 10.0.0.0 – 10.255.255.255
  • Class B: 172.16.0.0 – 172.31.255.255
  • Class C: 192.168.0.0 – 192.168.255.255

What is Vlan?

  • VLAN is a logical segmentation of a layer 2 broadcasts or l2 network.
  • By default the device is same VLAN can communicate.
  • VLAN Divides the broadcast domain and enhance the network security.
  • VLAN 1 is default or native VLAN for cisco switches only.

How to Create VLAN?

Open the terminal and login to Switch

Switch#en

Switch# configure terminal

Switch(Config)# vlan 10

Switch(Config-vlan)# name admin

Switch(Config-vlan)# end

Now you can assign any interface to this vlan.

Switch# Configure terminal

Switch(Config)# interface fa0/1

Switch(Config-if)# switchport mode access

Switch(Config-if)# switchport access vlan 10

Switch(Config-if)# end

What is Trunk?

Trunk is a port between 2 switches which carry frames of multiple VLAN.

Trunk Port Configuration

Switch(Config)# interface fa0/1

Switch(Config-if)# switchport mode trunk

Switch(Config-if)# end

What is VTP?

VTP(VLAN trunking protocol) is used for centralized management of VLANs

Example: Suppose we have more than 10+ Switches in the network and think about creating VLANs on each switch.

It’s hectic and time taking task.

Here comes VTP in action.

We create VLAN on a single switch  (in server mode) and after creation the VLAN information is forwarded to all the other switches in the network, switch synchronize their VLAN database depending upon configuration revised number.

VTP Modes

Server Mode           Transport Mode                 Client Mode

 

What is inter VLAN routing?

In a flat switch network broadcast is a biggest problem so we create VLANs to divide broadcast Domain.

  • By default device broadcast within the same VLAN.
  • By default VLAN 10 and VLAN 20 cannot communicate directly
  • To communicate between different VLANs there should be a L3 device / L3 interface between VLANs.
  • We have 2 solutions:1st  is Router and 2nd is Switched Virtual Interface (SVI) L3 Switch

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