Friday, November 18, 2011

Networking Interview Questions

Networking Interview Questions

·         Describe OSPF in your own words.
·         OSPF areas, the purpose of having each of them
·         Types of OSPF LSA, the purpose of each LSA type
·         What exact LSA type you can see in different areas
·         How OSPF establishes neighboor relation, what the stages are
·         If OSPF router is stucked in each stage what the problem is and how to troubleshoot it
·         OSPF hierarchy in the single or multi areas. Cool OSPF behavior in broadcast and nonbroadcast
·         Draw the diagram of typical OSPF network and explain generally how it works, DR, BDR, election, ASBR, ABR, route redistribution and summarization
·         How it works and the purpose
·         Diff types (SSTP, MSTP, RSTP) Cisco - PVST/PVST+
·         root election
·         Diff. port stages and timing for convergence
·         Draw the typical diagram and explain how diff types of STP work
·         What ports are blocking or forwarding
·         How it works if there are topology changes
·         What are they
·         Diff types
·         Write an example if you want to allow and to deny…
·         Well-known port numbers (DNS - 53 and etc…)
·         What is that
·         What is the diff b/w L2 and L3 QoS
·         How it works
·         Draw the typical network diagram you have to deal with
·         explain how it works
·         What part of it you are responsible
·         firewall, what is that, how it works, how it is diff from ACLs
·         What problems with the network you had had and how you solved it.
·         What are the ways to troubleshoot the network, techniques, commands
·         network security, ways to achieve it
·         VLANs
·         STP
·         How a L2 switch works with broadcast, unicast, multicast, known/unknown traffic
·         VRRP, GLBP
·         port monitoring and mirroring
·         L3 switch, how it works
·         PIM sparse and dense modes

Network engineer/architect interview questions

1.      Explain how traceroute, ping, and tcpdump work and what they are used for?
2.      Describe a case where you have used these tools to troubleshoot.
3.      What is the last major networking problem you troubleshot and solved on your own in the last year?
4.      What LAN analyzer tools are you familiar with and describe how you use them to troubleshoot and on what media and network types.
5.      Explain the contents of a routing table (default route, next hop, etc.)
6.      What routing protocols have you configured?
7.      Describe the commands to set up a route.
8.      What routing problems have you troubleshot?
9.      How do you display a routing table on a Cisco? On a host?
10.  How do you use a routing table and for what?
11.  What is a route flap?
12.  What is a metric?
13.  When do you use BGP, IGRP, OSPF, Static Routes?
14.  What do you see as current networking security issues (e.g. NFS mounting, spoofing, one time passwords, etc.)?
15.  Describe a routing filter and what it does.
16.  Describe an access list and what it does.
17.  What is a network management system?
18.  Describe how SNMP works.
19.  Describe the working environment you are currently in, e.g. frequent interruptions, frequent priority shifting, team or individual.
20.  What do you use to write documentation? Editor? Mail reader?
21.  What platform (s) do you currently work on at your desk?
22.  How do you manage multiple concurrent high level projects?
23.  Describe a recent short term stressful situation and how you managed it.
24.  How do you manage a long term demanding stressful work environment?
25.  Have you worked in an assignment based environment, e.g. work request/trouble ticket system, and if so, describe that environment.
26.  Describe what network statistics or measurement tools you are familiar with and how you have used them.
27.  Describe what a VPN is and how it works.
28.  Describe how VoIP works.
29.  Describe methods of QoS.
30.  How does ToS bit work?


  1. What is a default gateway? - The exit-point from one network and entry-way into another network, often the router of the network.
  2. How do you set a default route on an IOS Cisco router? - ip route x.x.x.x [where x.x.x.x represents the destination address]
  3. What is the difference between a domain local group and a global group? - Domain local groups grant permissions to objects within the domain in which the reside. Global groups contain grant permissions tree or forest wide for any objects within the Active Directory.
  4. What is LDAP used for? - LDAP is a set of protocol used for providing access to information directories.
  5. What tool have you used to create and analyze packet captures? - Network Monitor in Win2K / Win2K3, Ethereal in Linux, OptiView Series II (by Fluke Networks).
  6. How does HSRP work?
  7. What is the significance of the IP address - The limited broadcast address is utilized when an IP node must perform a one-to-everyone delivery on the local network but the network ID is unknown

Windows sysadmin interview questions

  1. What are the required components of Windows Server 2003 for installing Exchange 2003? - ASP.NET, SMTP, NNTP, W3SVC
  2. What must be done to an AD forest before Exchange can be deployed? - Setup /forestprep
  3. What Exchange process is responsible for communication with AD? - DSACCESS
  4. What 3 types of domain controller does Exchange access? - Normal Domain Controller, Global Catalog, Configuration Domain Controller
  5. What connector type would you use to connect to the Internet, and what are the two methods of sending mail over that connector? - SMTP Connector: Forward to smart host or use DNS to route to each address
  6. How would you optimise Exchange 2003 memory usage on a Windows Server 2003 server with more than 1Gb of memory? - Add /3Gb switch to boot.ini
  7. What would a rise in remote queue length generally indicate? - This means mail is not being sent to other servers. This can be explained by outages or performance issues with the network or remote servers.
  8. What would a rise in the Local Delivery queue generally mean? - This indicates a performance issue or outage on the local server. Reasons could be slowness in consulting AD, slowness in handing messages off to local delivery or SMTP delivery. It could also be databases being dismounted or a lack of disk space.
  9. What are the standard port numbers for SMTP, POP3, IMAP4, RPC, LDAP and Global Catalog? - SMTP – 25, POP3 – 110, IMAP4 – 143, RPC – 135, LDAP – 389, Global Catalog - 3268
  10. Name the process names for the following: System Attendant? – MAD.EXE, Information Store – STORE.EXE, SMTP/POP/IMAP/OWA – INETINFO.EXE
  11. What is the maximum amount of databases that can be hosted on Exchange 2003 Enterprise? - 20 databases. 4 SGs x 5 DBs.
  12. What are the disadvantages of circular logging? - In the event of a corrupt database, data can only be restored to the last backup.

Windows sysadmin interview questions

  1. What is Active Directory schema?
    The Active Directory schema contains formal definitions of every object class that can be created in an Active Directory forest it also contains formal definitions of every attribute that can exist in an Active Directory object.Active Directory stores and retrieves information from a wide variety of applications and services. So that it can store and replicate data from a potentially infinite variety of sources, Active Directory standardizes how data is stored in the directory. By standardizing how data is stored, the directory service can retrieve, update, and replicate data while ensuring that the integrity of the data is maintained.
1.      1) Schema master is a set of rules which is used to define the struture of active directory. It contains definitions of all the objects which are stored in AD. It maintains information and detail information of objects.
2) If there are many organisational units and to implement policy on all OUś we use Domain level policy.
4) Global Catalog Server maintains full information about its own domain and partial information about other domains. It is a forest wide role.
12) Sites: one or more well-connected highly reliable and fast TCP/IP subnets. A site allows administrator to configure active directory access and replication topology to take advantage of the physical network.
13) dcpromo to add/remove active directory but first ADC should be removed before DC if we want to remove DC first then check this server is last domain controller in domain.
16) I think the answer for this is schema master.
  1. What are the domain functional level in Windows Server 2003?

  1. What are the forest functional level in Windows Server 2003?
  2. What is global catalog server?
         A global catalog server is a domain controller it is a master searchable database that contains information about every object in every
domain in a forest. The global catalog contains a complete replica of all
objects in Active Directory for its host domain, and contains a partial replica
of all objects in Active Directory for every other domain in the forest.
It have two important functions:
i)Provides group membership information during logon and authentication
ii)Helps users locate resources in Active Directory

  1. How we can raise domain functional & forest functional level in Windows Server 2003?
  2. Which is the deafult protocol used in directory services?
  3. What is IPv6?
  4. What is the default domain functional level in Windows Server 2003?
  5. What are the physical & logical components of ADS
  6. In which domain functional level, we can rename domain name?
   All domain controllers must be running Windows Server 2003, and the Active Directory functional level must be at the Windows Server 2003.
Yes u can rename the domain in windows server 2003

  1. What is multimaster replication?
  2. What is a site?
  3. Which is the command used to remove active directory from a domain controler?
  4. How we can create console, which contain schema?
  5. What is trust?
  6. What is the file that’s responsible for keep all Active Directory database?

1.      1. Difference between Router and Routing: -
Router: -
Router is a device which is used to connect different network. A device or setup that finds the best route between any two networks, even if there are several networks to traverse. Like bridges, remote sites can be connected using routers over dedicated or switched lines to create WANs.
Routing: -
Process of delivering a message across one or more networks via the most appropriate path.
2. Dynamic Routing and Static Routing: -
Dynamic routing performs the same function as static routing except it is more robust. Static routing allows routing tables in specific routers to be set up in a static manner so network routes for packets are set. If a router on the route goes down the destination may become unreachable. Dynamic routing allows routing tables in routers to change as the possible routes change. There are several protocols used to support dynamic routing including RIP and OSPF

What is UTP?
UTP — Unshielded twisted pair 10BASE-T is the preferred Ethernet medium of the 90s. It is based on a star topology and provides a number of advantages over coaxial media:
It uses inexpensive, readily available copper phone wire. UTP wire is much easier to install and debug than coax. UTP uses RG-45 connectors, which are cheap and reliable.
What is a router? What is a gateway?
Routers are machines that direct a packet through the maze of networks that stand between its source and destination. Normally a router is used for internal networks while a gateway acts a door for the packet to reach the ‘outside’ of the internal network
What is Semaphore? What is deadlock?
Semaphore is a synchronization tool to solve critical-section problem, can be used to control access to the critical section for a process or thread. The main disadvantage (same of mutual-exclusion) is require busy waiting. It will create problems in a multiprogramming system, where a single CPU is shared among many processes.
Busy waiting wastes CPU cycles.
Deadlock is a situation when two or more processes are waiting indefinitely for an event that can be caused by only one of the waiting processes. The implementation of a semaphore with a waiting queue may result in this situation.
What is Virtual Memory?
Virtual memory is a technique that allows the execution of processes that may not be completely in memory. A separation of user logical memory from physical memory allows an extremely large virtual memory to be provided for programmers when only a smaller physical memory is available. It is commonly implemented by demand paging. A demand paging system is similar to a paging system with swapping. Processes reside on secondary memory (which is usually a disk). When we want to execute a process, we swap it into memory.


x86 interview questions

These interview questions test the knowledge of x86 Intel architecture and 8086 microprocessor specifically.
1.      What is a Microprocessor? - Microprocessor is a program-controlled device, which fetches the instructions from memory, decodes and executes the instructions. Most Micro Processor are single- chip devices.
2.      Give examples for 8 / 16 / 32 bit Microprocessor? - 8-bit Processor - 8085 / Z80 / 6800; 16-bit Processor - 8086 / 68000 / Z8000; 32-bit Processor - 80386 / 80486.
3.      Why 8085 processor is called an 8 bit processor? - Because 8085 processor has 8 bit ALU (Arithmetic Logic Review). Similarly 8086 processor has 16 bit ALU.
4.      What is 1st / 2nd / 3rd / 4th generation processor? - The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.
5.      Define HCMOS? - High-density n- type Complimentary Metal Oxide Silicon field effect transistor.
6.      What does microprocessor speed depend on? - The processing speed depends on DATA BUS WIDTH.
7.      Is the address bus unidirectional? - The address bus is unidirectional because the address information is always given by the Micro Processor to address a memory location of an input / output devices.
8.      Is the data bus is Bi-directional? - The data bus is Bi-directional because the same bus is used for transfer of data between Micro Processor and memory or input / output devices in both the direction.
9.      What is the disadvantage of microprocessor? - It has limitations on the size of data. Most Microprocessor does not support floating-point operations.
10.  What is the difference between microprocessor and microcontroller? - In Microprocessor more op-codes, few bit handling instructions. But in Microcontroller: fewer op-codes, more bit handling Instructions, and also it is defined as a device that includes micro processor, memory, & input / output signal lines on a single chip.
11.  What is meant by LATCH? - Latch is a D- type flip-flop used as a temporary storage device controlled by a timing signal, which can store 0 or 1. The primary function of a Latch is data storage. It is used in output devices such as LED, to hold the data for display.
12.  Why does microprocessor contain ROM chips? - Microprocessor contain ROM chip because it contain instructions to execute data.
13.  What is the difference between primary & secondary storage device? - In primary storage device the storage capacity is limited. It has a volatile memory. In secondary storage device the storage capacity is larger. It is a nonvolatile memory. Primary devices are: RAM / ROM. Secondary devices are: Floppy disc / Hard disk.
14.  Difference between static and dynamic RAM? - Static RAM: No refreshing, 6 to 8 MOS transistors are required to form one memory cell, Information stored as voltage level in a flip flop. Dynamic RAM: Refreshed periodically, 3 to 4 transistors are required to form one memory cell, Information is stored as a charge in the gate to substrate capacitance.
15.  What is interrupt? - Interrupt is a signal send by external device to the processor so as to request the processor to perform a particular work.
16.  What is cache memory? - Cache memory is a small high-speed memory. It is used for temporary storage of data & information between the main memory and the CPU (center processing unit). The cache memory is only in RAM.
17.  What is called .Scratch pad of computer.? - Cache Memory is scratch pad of computer.
18.  Which transistor is used in each cell of EPROM? - Floating .gate Avalanche Injection MOS (FAMOS) transistor is used in each cell of EPROM.
19.  Differentiate between RAM and ROM? - RAM: Read / Write memory, High Speed, Volatile Memory. ROM: Read only memory, Low Speed, Non Voliate Memory.
20.  What is a compiler? - Compiler is used to translate the high-level language program into machine code at a time. It doesn.t require special instruction to store in a memory, it stores automatically. The Execution time is less compared to Interpreter.
21.  Which processor structure is pipelined? - All x86 processors have pipelined structure.
22.  What is flag? - Flag is a flip-flop used to store the information about the status of a processor and the status of the instruction executed most recently
23.  What is stack? - Stack is a portion of RAM used for saving the content of Program Counter and general purpose registers.
24.  Can ROM be used as stack? - ROM cannot be used as stack because it is not possible to write to ROM.
25.  What is NV-RAM? - Nonvolatile Read Write Memory, also called Flash memory. It is also know as shadow RAM.


Cannavaro said...


I read this post 2 times. It is very useful.

Pls try to keep posting.

Let me show other source that may be good for community.

Source: Network controller interview questions

Best regards

vamshi krishnam raju said...

Hi Cannavaro , Yeah sure i will try to post some more questions very soon

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