Top 20 CCNA Interviews Questions
1) What is difference between hub and switch?
Hub
• layer 1- unintelligent device
• it never looks for mac address or ip address
• always broadcast
• single broadcast domain, single collision domain
• it always operates at half duplex
Switch
• Layer 2- intelligent device
• Forwards the frame based on mac address
• If the destination is unknown it will broadcast, else unicast
• Single broadcast domain and multiple collision domain
• Either half duplex or full duplex
2) what is difference between switch and router?
switch
• layer 2- intelligent device
• it maintains the mac table
• forwards the frames based on mac address
• if destination is unknown it will broadcast else unicast
• single broadcast domain and multiple collision domain.
Router
• layer 3- intelligent device
• it maintains the routing table
• forwards the packet based on ip address
• if the destination is known it routes the packet else discards the packet.
• multiple broadcast domain and multiple collision domain.
3) what is difference between layer 2 switch and layer 3 switch?
Layer 2 switch
• it does only switching
• forwards the frames based on mac address
• it maintains the mac table
Layer 3 switch
• It does both switching and routing
• forwards the frames based on mac address and forwards the packets based on ip address.
• it maintains both mac table and routing table
4) what is difference between layer 3 switch and router?
Layer3 switch
• it does both switching and routing
• it maintains mac table and routing table
• it prefers for inter vlan routing
Router
• it does only routing
• it maintains only routing table.
• it prefers to connect wan technologies
5) what are all the private ip address range?
Private ip Class range
Class A
Private IP: 10.0.0.0
Range: 10.0.0.1 to 10.255.255.255
Class B:
Private IP: 172.16.0.0 to 172.31.0.0
Range: 172.16.0.1 to 172.31.255.255
Class C:
Private IP: 192.168.0.0
Range: 192.168.0.1 to 192.168.255.255
6) define mac address?
• The media access control address is unique that assigned to network interface card.
• mac address length is 48 bits, first 24 bits represents the OUI and next 24 bits varies with respective machines.
• mac address is represents in hexa decimal format.
7) Which command used to check the MAC address of the computer?
IP config /all
8) Which command used to check the MAC address of the switch?
Show version
9) Which command is used to check the MAC address of the router?
Show interface < interface Type >
10 How many MAC address will be present in the Computer?
Generally, one because most of the host have a single NIC. Sometimes server will have more than one NIC card; in that case MAC address will be equal to the number of NIC.
11) Is it possible to have more than one MAC address in a computer?
Yes, if you insert more than one NIC card then you can have multiple MAC address for the same computer. Now a day’s normal laptop have multiple MAC address for the Bluetooth adapter, Ethernet adapter, wireless LAN adapter.
12) define ip address?
• internet protocol address is 32 bits that assigned to the tcp/ip adapter
• ip address classes are A,B,C,D,E
• ip address is represented in dotted decimal notation.
13) what is the range of Class A IP address ?
1.0.0.0 to 126.0.0.0
14) what is the range of Class B IP addres?
128.0.0.0 to 191.0.0.0
15) what is the range of Class C IP address ?
192.0.0.0 to 223.0.0.0
16) what is the range of class D IP address?
2240.0.0. to 239.0.0.0
17) what is the range of class E IP address?
240.0.0.0 to 255.255.255.254
18) what is the use of IP address 0.0.0.0?
The IP address is reserved for any network , mainly used in configuration of default route towards the ISP network.
19) Define Loopback IP address?
The loopback IP address or local host IP address is used to test the TCP IP stack and connectivity of TCP/IP stack to the network adapter.
The reserved IP address is 127.0.0.0/8
We can check the TCP IP stack by Ping-ing the loopback IP address without connecting the particular host to the network.
It’s applicable only for PC not for router or else switch.
20) What will be the result of ping 127.0.0.1 among the switch or router?
It doesn’t work, will be request time out /unsuccessful.
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