CISCO ACI INTERVIEW QUESTIONS

CISCO ACI INTERVIEW QUESTIONS :-

What is mean by Fabric Path ?

What is the difference between software based controller & hardware based controller ?

What is the advantages of ACI over legacy datacenter?

Define ACI Fabric discovery process ?

What is the role of APIC controller in ACI ?

Assume all APIC is down now, a server administrator is trying to do vmotion from one ESXI to another ESXI connected to different switch.  With this move will be successful ?  

What is meant by VNI & VTEP ?

Explain frame header and packet header

How many vxlan are supported ?

How many vlan supported in legacy ?

What is mean by Flood and Hardware proxy table ?

What is mean by IPN ?

Where multicast is used in ACI ?

In network centric model how MAC address get synchronized between Legacy and ACI ?

Is contracts are statefull or stateless ?

Explan the ACI fabric initilaization process ?

What is mean by flood and hardware proxy ?

Explain the steps to configure L3Out ?

Please do contribute if there you have any questions. this might be helpful for those who are aspiring carrier in ACI.

F5 LTM Interview Questions for Network Engineers

 

1. Explain  SSL offloading vs SSL bridging vs SSL pass-through.

2. What is mean by self IP address.

3. What is mean by floating self IP address.

4. What is SNAT.

5.  What are the various types of virtual servers.

6. What are the various load balancing methods available.

7. How many ways F5 can be deployed.

8. What is mean by TMOS.

9. What is mean by device group?

10. Maximum how many F5 can be in a device group?

11. What is mean by TLS and MTLS.

12. What is mean by TCP half open.

13. What is an iRule.

14. How will you t-shoot application performance issues hosted in F5 ?

Interview Questions for Senior Network Engineer

 Hi All,

I would like to share my interview questions for Senior Network Engineer role in Virtustream company.

Job Designation - Senior Advisor - IT Network Development Engineer.

Company - Virtustream (Dell Subsidiary)

Location - Bengaluru.

Below are list of questions asked during technical round.

Nexus questions :

1. What is the minimum BW required for a VPC peer link

2. what happens if Peer link goes down ? will it impact any servers ? what happen to data plane and control plane traffic

3. What happens if peer keepalive link goes down ?  will there be any impact 

4. Can we keep the peer-keepalive link down for long time ?

5. consider we have VPC configured for a server  with two uplinks of each 10G.  What will be the throughput on the server.

Switching Questions:

6. How RSTP works

7.  What are the steps to create a vlan 100 in switch ?

8.  What command will you use to allow additional vlan  ( id 100 ) to the exiting trunk port where already some vlans are allowed.  

9.  What command will you use to delete a vlan  ( id 100 ) from the exiting trunk port where already some vlans are allowed.  

OSPF Questions:

10. How many ways you can advertise network in OSPF?

11. WHat is the command used to check what are all interfaces participate in OSPF ?

12. How will you t-shoot if the OSPF between two routers are not coming up and stuck in exstart state?

13.   We are running OSPF in a  broadcast environment  with 4 routers.  what will the state of  routers which doesn't elected as DR and BDR routers ?

14. We have configured 2 subnets ( 10.1.1.1/24 & 20.1.1.1 /24 )  in OSPF broadcast environment. 

How many DR and BDR will be elected ?

15. you have not advertised a subnet in to OSPF via network and redistribute commands but when you issue  " show ip ospf interface "  command you see one interface was running OSPF , what could be the reason. ? 

16. If we are running two OSPF process in a router. how many database will be mainintined by the router ?

17.  How to advertise routes between one OSPF process to other OSPF process in same router

BGP Questions:

18 , what is mean by VRF lite.  

19.  what mechannism is used by BGP to avoid loop in IBPG and EBGP

20. We have configured loopback IP address in two BGP routers , how ever they couln't establish BGP session , what could be reason. 

ASA Questions:

21. ASA is sending traffic to different interface instead of DMZ interface , what could be the reason ?

22. list out commands to configure active /standby in ASA

23. Explain packet flow in ASA

24. what is identity NAT

25. What are the various types of NAT in ASA

26. we have configured site 2 site vpn  and we observed encrypted packets counts are increasing  at our end , but seeing no decrypted packets . what could be the reason ?

27. In the above same scenario , we see packets are decrypting but not getting encrypted ?  

F5 Questions:

28. What is mean by SNAT in F5

29. what happens if SNAT is not configured

30. what is mean by persistence and its types 

31. what could be reason if we see the F5 standby unit status as disconnected.

******** END ************

Network Engineer Interview Questions

Interview Questions :

1.  Tell about yourself ?

2.  What is the recent incident you faced in your job and how you troubleshoot ?

3.  Can you explain about OSI layers ?

4.  Can you brief the functions of each layers ?

5.  What are the protocols used in each layers ?

6.  What do you mean by routed and routing protocols ?

7.  Can you define link state routing and distance vector routing protocol with examples ?

8.  what is the difference between rip v1 and rip v2 ?

9.  How a neighbor is confirmed in EIGRP ?

10. In eigrp how a router informs that his neighbor is down to other routers ?

11. what is mean by stuck in active ?

12.  How will you clear a route which is in stuck in active state ?

13. what is mean by feassible successor and feasible distance ?

14. can you tell the metric calculation formula in EIGRP ?

15.  What is the difference between EIGRP and OSPF ?

16.  What is the metric used in OSPF and how it is calculated ?

17.  Explain about areas in OSPF ?

18. What is the difference between STUB , NSSA ,and TOTALLY STUB area of OSPF?

19.  what is mean by virtual-link and how many areas can  a virtual link pass ?

20.  How router id is selected in OSPF ?

21. Can we manually set router id , and how it affect the topology ?

22.  Which switch models you worked ?
23.  What is the difference between Cisco 4507 and Cisco 4507 E ?
24.  How data packets are switched in layer 2 ?

Interview Questions

1. What is the difference between the ASA firewall operating in Routed Mode and Transparent Mode ?

    Ans  :  A firewall in a routed mode is a routed hop and acts as a default gateway for hosts that connect to one of its screened subnets. . A transparent firewall, on the other hand, is a Layer 2 firewall that acts like a "bump in the wire," or a "stealth firewall," and is not seen as a router hop to connected devices.

2. How to control ARP Traffic in Transparent mode of ASA Firewall ? 

    Ans :  ARP Inspection is used to control ARP Traffic

3.  What is mean by Stealth Firewall ?

Ans  :

4.  What are called Non-IP Traffic?

Ans : AppleTalk, IPX, BPDUs, and MPLS

5. What happen when you change the mode of firewall from Routed to Transparent ?

Ans : When you change modes, the adaptive security appliance clears the configuration because many commands are not supported in both modes.

6. what are the different types of NAT supported by ASA ?
Ans :  i. Static NAT

         ii. Dynamic NAT
        iii. Static PAT
        iv. Dynamic PAT
         v. Identity NAT
        vi. Static Identity NAT
       vii. NAT Exemption
  

7. What is mean by Load Balancing?
In firewall, load balancing means the two firewall are configured in such a way that both the firewall will process the client request based on specific algorithm ( such as Round Robin Algorithm ) 

8. What is the use of VPN ?
       VPN is used to create a seperate tunnel between two users to have a secure connection which means the data is encapsulated before sending.

9.  What is the use of Proxy ARP ?
 Ans :  Proxy ARP feature will enable the device to answer the ARP queries for the network address that is not on that network

10. What is mean by Policy Based NAT?

11. Can you explain about OSI Model ?
   Ans :  OSI model is develpoped to have a common reference model for communication between devices of different vendors. It consists of seven layers 
       The bottom layer in OSI model is  ''Physical Layer '' which is responsible for forming a physical interfaces between devices which allows for transmission of data in raw bit stream.
       The second bottom layer is " Data Link Layer"  which is responsible for


12. What do you mean by Access List?
  Ans :  Routers ,Cisco ASA firewall provide traffic filtering capabilities using the access-list . Access list consists of ACE ( Access Control Entries ). An ACE is a single entry which permits or deny based on Protocol , Source and Destination address and can also be used source and destination port numbers

Cisco ASA supports mant Access list types
1.  Standard Access List
2.  Extendd Access List
3.  Ethertype Access List
4.  Web based Access List
5.  IPv6 Access List

13.  Differnce between TCP and UDP

	TCP	UDP
Acronym for:	Transmission Control Protocol	User Datagram Protocol or Universal Datagram Protocol
Function:	As a message makes its way across the internet from one computer to another. This is connection based.	UDP is also a protocol used in message transport or transfer. This is not connection based which means that one program can send a load of packets to another and that would be the end of the relationship.
Usage:	TCP is used in case of non-time critical applications.	UDP is used for games or applications that require fast transmission of data. UDP's stateless nature is also useful for servers that answer small queries from huge numbers of clients.
Examples:	HTTP, HTTPs, FTP, SMTP Telnet etc...	DNS, DHCP, TFTP, SNMP, RIP, VOIP etc...
Ordering of data packets:	TCP rearranges data packets in the order specified.	UDP has no inherent order as all packets are independent of each other. If ordering is required, it has to be managed by the application layer.
Speed of transfer:	The speed for TCP is slower than UDP.	UDP is faster because there is no error-checking for packets.
Reliability:	There is absolute guarantee that the data transferred remains intact and arrives in the same order in which it was sent.	There is no guarantee that the messages or packets sent would reach at all.
Header Size:	TCP header size is 20 bytes	UDP Header size is 8 bytes.
Common Header Fields:	Source port, Destination port, Check Sum	Source port, Destination port, Check Sum
Streaming of data:	Data is read as a byte stream, no distinguishing indications are transmitted to signal message (segment) boundaries.	Packets are sent individually and are checked for integrity only if they arrive. Packets have definite boundaries which are honored upon receipt, meaning a read operation at the receiver socket will yield an entire message as it was originally sent.
Weight:	TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control.	UDP is lightweight. There is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP.
Data Flow Control:	TCP does Flow Control. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control.	UDP does not have an option for flow control
Error Checking:	TCP does error checking	UDP does error checking, but no recovery options.
Fields:	1. Sequence Number, 2. AcK number, 3. Data offset, 4. Reserved, 5. Control bit, 6. Window, 7. Urgent Pointer 8. Options, 9. Padding, 10. Check Sum, 11. Source port, 12. Destination port	1. Length, 2. Source port, 3. Destination port, 4. Check Sum
Acknowledgement:	Acknowledgement segments	No Acknowledgment
Connection:	TCP is a connection-oriented protocol.	UDP is a connectionless protoc

Interview Questions with Cisco for post of Network Engineer

Interview Questions with Cisco:-

Hi folks recently i have attended interview with cisco for the post of Network Engineer . So i would like to post the interview questions in by blog. I hope this post will be helpfull for those who are preparing for interview .

   1.        Tell about your job profile ?

   2.       Explain about OSI layers ?

   3.       Do we use OSI layers now ? 

   4.       Explain about ARP works?

   5.       Scenario 1 : Explain how communication between PCA and PCB happens ?

   6.       What is the difference between OSI layer and TCP/IP Protocol?

   7.       What is the difference between TCP and IP ?

   8.       How much you know about RIP ?

   9.       What are the difference between RIPv1 and RIP v2?

   10.   Whether auto-summarisation is enable by default in RIP ? 

   11.   How auto-summarization works ?

   12.   Scenario 2 : How auto summarization works in this topology?

   13.   What do you mean by static routing and Default Static routing?

   14.   What do you mean by routed protocols and routing protocols ?

   15.   What is mean by AD value and Metric Value ?

   16.   How much you know about EIGRP ?

   17.   What is mean by Stuck in Active in EIGRP ?

   18.   What is the method to avoid Stuck  in active state ?

   19.   What is mean by Fessiable Successor ?

   20.   Whether it is possible to have two routes with for same destination ?

   21.   How much you know about OSPF ?

   22.   Explain how OSPF protocol works ?

   23.   How much you know about BGP?

   24.   How HSRP works ?

   25.   How STP protocol works ?

   26.   How is Root bridge is elected ?

   27.   What is the method to manually elect the root bridge?

   28.   What type of NAT you used in ASA firewall ?

   29.   What is the difference between Static Nat, Dynamic Nat and Policy Nat ?

   30.   You are worked in Cisco 6509 catalyst switch , so what is the supervisor engine model supported in Cisco 6509 switch ?

   31.   What type of redundancy you configured in Supervisor engine of your switch ?

   32.   What is mean by SSO mode ?

Cognizant - Interview Questions for Network Admin

Dear all,
       I have attended interview for the post of Network Admin on 31st August 2013. I would like the share the experience with you , that's why i am posting the list of interview questions asked to me.

I am just posting just the technical questions alone

1. What is mean by stuck in active in EIGRP ? 
2. What is mean by Feasible Sucessor ?
3. What  is it located ?
4. What are the metrics used in EIGRP ?
5. What are the default values of Metric ?
6. What is the Multicast address used in EIGRP ?
7. What do you mean by unequal cost load balancing ?
8. what is the formula to calculate metric ?
9. what is the condition for feasible distance ?
10. next come to OSPF , What do you mean by LSA in OSPF ?
11. What are the different states in OSPF ?
12. when will the database description packet gets exchanged ?
13. what are the contents in database description packet  ?
14. What do you mean by Type 6 LSA ?
15. In a site to site vpn how many phases are there ?
16. What are the parameters of Phase 1 ?
17. If the authentication method in phase 1 mismatch ,how will you identify ?
18. How will check the configured Access-List is working or not ?
19. What is the use of having Security Zones in ASA Firewall ?
20. What are the parameters you will check if i cannot able to communicate from inside  n/w to outside n/w through the ASA firewall ?
21. How will you check whether NAT is happening or not ?

Network Management Software - LAN Management Soultion

Cisco Works Lan Management Solution :

    The need for computers in this world are increasing day by day and the most important things is to have a connection between these computers so therr is need for network devices like switches , Routers and Firewalls.
    The toughest job for Network Administrators is to administrator all the network devices from one place. Cisco systems has come with an solution called Cisco Works LAN Management Solution which is a software used to managemt and troubleshoot network devices.

LMS 3.2 Features :

1. Campus Manager
2. Common Services
3. Device Fault Management
4. Health And Utiliziation Monitors
5. Internetwork Performance Monitors
6. Resource Manager Essentials

ASA Firewall

Hi Readers ,

           Today i am going to post about the Security Appliance ( i.e Adapative Security Appliance )

Cisco Develops Security appliance for all kinds of customers vary from small , medium sized to large organizations.

Various models of ASA firewall :

1. Cisco 5505

2. Cisco 5510

3. Cisco 5520

4. Cisco 5540

5. Cisco 5550

6. Cisco 5580

7. Cisco 5585 X

Functional Overview of a Firewall :

Firewall Mode :
a. Routed Mode -
     
b. Transparent Mode -

-> A transparent firewall, on the other hand, is a Layer 2 firewall that acts like a "bump in the wire," or a "stealth firewall," and is not seen as a router hop to connected devices.
-> Layer 3 traffic, such as IP traffic, cannot pass through the security appliance unless you explicitly permit it with an extended access list.
->  The only traffice can pass through transparent firewall is ARP traffic which can be controlled by arp inspection
  

Differnce Between HSRP and VRRP Protocol

 I hope this blog will be usefull to those who want to understand the difference between HSRP and VRRP.Both the protocols are widely used by Network professional to achieve gateway load-balancing .The More about these protocols are listed below.

HSRP :
->  HSRP stands for Hot Standby Routing Protocol
->  Cisco Properiotity Protocol
->  Preempt is diabled by default
->  HSRP Router terms Active Router, Standby Router

VRRP :
->  VRRP stands for Virtual Router Redundancy Protocol
->  Open Standard Protocol
->  Preempt is enable by default
->  VRRP Router terms Master Router, Backup Router