Network Operations Center (NOC) Interview Questions & Answers

  1. Question 1. What Type Of Firewall Can Be Used To Block A Web Security Threat?

    Answer :

    A web application firewall or a layer 7 firewall can be used for the purpose.

  2. Question 2. Which Fields In A Packet Does A Network Layer Firewall Look Into For Making Decisions?

    Answer :

    IP and transport layer headers for information related to source and destination IP addresses, port numbers etc.

  3. ITIL Configuration Management Interview Questions

  4. Question 3. Which Feature On A Cisco Firewall Can Be Used For Protection Against Tcp Syn Flood Attacks?

    Answer :

    TCP intercept feature.

  5. Question 4. Which Feature On A Firewall Can Be Used To Block A Specific Url Or A Website?

    Answer :

    URL Filtering.

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  7. Question 5. Which Is The Main Field In An Ip Header , Which Is Modified By A Nat Firewall?

    Answer :

    The source IP address in the IP header.

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  9. Question 6. What Type Of Firewall Can Be Configured For Providing User Based Authentication To Users On The Lan Network.?

    Answer :

    Proxy firewall.

  10. Question 7. How To Troubleshoot A High Cpu Utilization Problem In A Router?

    Answer :

    This symptom is the sign of abnormal functionality in a router. First we should know the exact reason for increased CPU utilization, and we can use “show processes cpu ,” “show interface stat” commands to check the process utilizations. It could be due to high traffic flow (congestion), complex ACL or VPN deployments, ARP/TCP issues etc.

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    Switching Interview Questions

  12. Question 8. If A Router’s Wan Link Goes Down, What You Will Do In That Situation?

    Answer :

    First we need to verify the exact reason for failover; it could be due to physical or protocol issues. If it is a “protocol down” problem, then valid reasons could be link authentication failure, encapsulation mismatch, clock rate not configured, improper access control, MTU or Duplex mismatch, etc.

  13. Question 9. Is It Normal To Get Crc Errors On Mpls Wan Links?

    Answer :

    It could be normal if it is less than 1% of total traffic on that interface with no packet drop

    And it is recommended to resolve link issues in case cyclic redundancy check (CRC) errors are more than 1% of the total interface traffic. The most common reason for receiving CRC errors is the duplex setting, as most of providers set their interface to “auto” mode.

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  15. Question 10. If My Bgp Neighbor Is Stuck In Idle, Or Active State, What Should I Do?

    Answer :

    If BGP peer is in idle state then it could be due to physical connectivity failure or neighbor is not defined with properly with respective AS. In connect state, BGP tries to establish TCP session over port number 179 if it fails to establish TCP connection then it goes to Active state where it retries to establish TCP connection. By using debug ip bgp and debug ip tcp transactions commands, we can find out the exact cause of TCP connection failure. Lack of “update-source” or “ebgp-multihop” command can also be a reason for neighbor active state;

  16. Question 11. What Does “%ospf-5-nbrstate: Ospf-1 [5330] Process 1, Nbr On Vlan44 From Full To Exstart, Badseqnum Ospf” Log Message Mean?

    Answer :

    This log message pops up when an OSPF DBD exchange process uses a bad sequence number (due to packet loss or packet exploitation) for the synchronization of the database with its neighbors.

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  18. Question 12. What Is The Significance Of The Variable Ip-ospf-transmit-delay?

    Answer :

    If OSPF is configured on low bandwidth links, IP-OSPF-Transmit-Delay is used to increase the time of the age field of a LSA update. By default it is set to 1 second and, to make it effective, it must be added before transmission over a link.

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  20. Question 13. How To Perform Password Recovery In A Switch?

    Answer :

    Every switch series has its own set of recovery methods. Here you can describe the procedure of password recovery for the switches on which you have shown your work experience. You can also refer following links to get an idea of password recovery on well-known Cisco switches.

  21. Question 14. What Will Happen If One Of The Ports Goes Down Of An 8 Port Etherchannel?

    Answer :

    The overall bandwidth of an EtherChannel interface depends on its active member links. An EtherChannel with 8 active 100 Mbps links should indicate a bandwidth of 800 Mbps and, if one of its physical ports fails, the available bandwidth of port-channel interface will be evaluated as 700Mbps without flapping the port-channel.