Network Interview Question and Answer - set 3

1Question 21 .       Difference between CAM and MAC table?

Answer : CAM maps ports to the MAC addresses found on the ports.  ARP matches IP addresses to MAC addresses.

MAC-ADDRESS-TABLE: kept by Layer-2 devices only.
MAC-ADDRESS-ENTRY - Layer-2 unicast/multicast/broadcast destination.

ARP-TABLE: Kept by routers and L3 switches - L3 devices only.
ARP-ENTRY: Layer-3 unicast/multicast/broadcast destination to layer-2 unicast/multicast/broadcast destination mapping.

if you understand the difference between routing and switching then that should be enough.

Now a switch can be in both layer-2 and layer-3 so it will have both.

2Question 22 .       In switch, FA 0/1 to FA0/15 port is Access port and FA0/16&FA0/17 trunk port. What command used to make default port (two line command)?

Answer : Switch(config):interface range FA0/17 Switch(config-if):no Switchport mode

Question 23.      HSRP : if two routers (R-1 and R-2)

R-1 priority 150

R-2 priority 100

preempt is enabled on both of them. Assume there was booting delay on R-1. so R-2 will be the Active gateway. When R-1 has been booted and be ready, will it take the role of Active router ?? or it will wait until R-2 fails ??

Answer : if two devices have preemt enabled, the one with the highest priority will become "active". This is regardless of the boot order. The higher priority hsrp messages should force the lower priority to go back through the HSRP process and land at "standby".

Question 24.      Configuration on DHCP in order to get IP address(ip pool) where we can specify the range if ip address from DHCP server and we are doing IP subnetting in order to utilize the ip address as per the requirement of local network..

If we use DHCP and subnetting in local area network? What is the difference between two of them? 

Answer : dhcp has nothing to do with creating subnets, it is just a protocol that dynamically assigns ip addresses to devices in a subnet.  its just to help save us the work of manually putting ip addresses on each machine.

Subnet was created by the administrator, we use dhcp to help us allocate the range of addresses that was created when the subnet was created.

Question 25 . Types of BPDUs?

Answer : Three types of Bridge Protocol Data Units (BPDUs) are Configuration BPDU (CBPDU), Topology Change Notification (TCN) BPDU and Topology Change Notification Acknowledgment (TCA).

Question 26.      What is the difference between broadcasting and flooding?

Answer : Broadcasting – It will happened only within the broadcast domain

Flooding : Frames will flood to all the ports, like STP, CDP, DTP frames( if switch have default configuration)

Question 27.      What are the advantages of PPP protocol?

Answer : i. Error detection for each transmitted frame through the use of a CRC code in each frame header.

ii. Support for authentication of the connection using multiple authentication protocols. (PAP & CHAP)

iii. A key advantage of PPP is that it is an extensible protocol suite like PPPoE & PPPoA.

Question 28.      RIP, EIGRP & OSPF using TCP or UDP and it’s port number?

RIP –  UDP – 520

RIPnG – UDP – 521 (IPV6)

EIGRP – TCP – 88

OSPF – TCP - 89

Question 29.       what will happen if we send  untagged packet to a tagged port?

Answer : Access port will discard the frame because access port don’t know the vlan tagged frame.

Question 30.  What is loopback interface and where it is used?

Answer : Loopback interface is virtual interface. Loopback addresses are great for management and if utilized properly can be a great tool to ping and check if your routers are up and running