MCSE Interview Questions & Answers

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MCSE Interview Questions & Answers

Do you have MCSE certification? Are you in job search? Need a suitable job matching your skills? MCSE stands for Microsoft Certified Systems Engineer which is senior level credential from Microsoft. MCSA is an entry level credential. If a candidate has this credential then he is allowed to go to expert level. This certification can be received after writing many exams and other proficiency tests. Search and apply for the multiple jobs on MCSE posted on wisdom jobs. Related jobs in MCSE including cloud architect, compute operations and delivery lead, trainee engineer, technical support engineer, system security, senior IT network engineer, windows server administrator, active directory administrator, senior technical support engineer and stitch support etc. Following MCSE job interview questions and answers are helpful for your job search.

MCSE Interview Questions

MCSE Interview Questions
    1. Question 1. What Is An Ip Address?

      Answer :

      An IP address (or Internet Protocol address) is a unique address that certain electronic devices use in order to identify and communicate with each other on a computer network using Internet protocol. It is a logical address assigned to a device in the network. Current version of IP address is Ipversion6. it is a 128 bit address. But it is not largely implemented. Current popular version in Ipv4. it is a 32 bit address. For example 61.11.124.160. IP addresses are managed and created by the Internet Assigned Numbers Authority (IANA). The IANA generally allocates super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to Internet Service Providers (ISP) and enterprises.

    2. Question 2. What Is A Subnet Mask?

      Answer :

      A mask used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. For example, consider the IP address 150.215.017.009. Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network.

    3. Question 3. What Is Arp?

      Answer :

      Address Resolution Protocol (ARP) is a network protocol, which maps a network layer protocol address to a data link layer hardware address. For example, ARP is used to resolve IP address to the corresponding Ethernet address.

    4. Question 4. To Which Osi Layer Does Arp Belong?

      Answer :

      ARP belongs to the OSI data link layer (Layer 2). ARP protocol is implemented by the network protocol driver. ARP packets are encapsulated by Ethernet headers and transmitted.

    5. Question 5. Which Rfc Specify The Requirements For Arp?

      Answer :

      RFC 826 specifies the ARP packet format and other details.

    6. Question 6. What Is The Use Of Arp?

      Answer :

      A host in an Ethernet network can communicate with another host, only if it knows the Ethernet address (MAC address) of that host. The higher level protocols like IP use a different kind of addressing scheme (like IP address) from the lower level hardware addressing scheme like MAC address. ARP is used to get the Ethernet address of a host from its IP address. ARP is extensively used by all the hosts in an Ethernet network.

    7. Question 7. Why A Ip Address Needs To Be Mapped To A Mac Address, Why Can't The Mac Address Itself Is Represented Using The Ip Address?

      Answer :

      The length of a MAC address is 6 bytes and the length of an IP address is 4 bytes. Obviously, the MAC address cannot be represented using the IP address. So an IP address must be mapped to the corresponding MAC address.

    8. Question 8. Can Arp Be Used In A Network Other Than Ethernet?

      Answer :

      ARP is a general protocol, which can be used in any type of broadcast network. The fields in the ARP packet specifies the type of the MAC address and the type of the protocol address. ARP is used with most IEEE 802.x LAN media. In particular, it is also used with FDDI, Token Ring, and Fast Ethernet, in precisely the same way as it is with Ethernet.

    9. Question 9. How Does Arp Resolve An Ip Address To An Ethernet Mac Address?

      Answer :

      When ARP needs to resolve a given IP address to Ethernet address, it broadcasts an ARP request packet. The ARP request packet contains the source MAC address and the source IP address and the destination IP address. Each host in the local network receives this packet. The host with the specified destination IP address, sends an ARP reply packet to the originating host with its IP address.

    10. Question 10. What Is An Arp Cache?

      Answer :

      ARP maintains the mapping between IP address and MAC address in a table in memory called ARP cache. The entries in this table are dynamically added and removed.

    11. Question 11. When Is An Arp Request Packet Generated?

      Answer :

      The following steps results in the generation of an ARP request packet:

      • The IP module sends a packet, destined for another host in the network, to the ARP module.
      • The ARP module looks up the ARP table (cache) to resolve the IP address.
      • If the supplied IP address is present in the ARP cache, it is resolved into its Ethernet address.
      • If the ARP module is not able to find an entry for this IP address in the ARP cache, then it sends an ARP request packet to the Ethernet driver, to resolve the IP address to the Ethernet address.
      • After the IP address is resolved by the ARP module, the packet is sent to the Ethernet driver for transmission.

    12. Question 12. What Happens When A Host Receives An Arp Request Packet?

      Answer :

      The ARP request is received and processed by all the hosts in the network, since it is a broadcast packet. The following steps are carried out when a ARP request packet is received by a host:

      • If the IP address to be resolved is for this host, then the ARP module sends an ARP reply packet with its Ethernet MAC address.
      • If the IP address to be resolved is for this host, then the ARP module updates its ARP cache with the source Ethernet MAC address to source IP address mapping present in the ARP request packet. If the entry is already present in the cache, it is overwritten. If it is not present, it is added.
      • If the IP address to be resolved is not for this host, then the ARP module discards the ARP request packet.

    13. Question 13. What Is The Disadvantage If A Host Updates Its Arp Cache Upon Receiving Any Arp Request?

      Answer :

      The host will exhaust the ARP cache with a lot of unused ARP entries, if it updates the ARP cache for any ARP request.

    14. Question 14. What Happens When A Host Receives An Arp Reply Packet?

      Answer :

      The ARP reply packet is received only by the host, which transmitted the ARP request packet. The ARP module adds the Ethernet hardware address to IP address mapping present in the ARP reply packet to the ARP cache.

    15. Question 15. Is There A Separate Packet Format For Arp Request And Arp Reply?

      Answer :

      No. Both the ARP request and ARP reply packets use the same format.

    16. Question 16. Which Mac Address Is An Arp Request Directed To?

      Answer :

      All ARP request packets are transmitted with the Ethernet broadcast address, so that all hosts in the network will receive the request.

       

    17. Question 17. To Which Mac Address Is An Arp Reply Packet Directed To?

      Answer :

      ARP reply packet is directed to the host, which transmitted the ARP request packet.

    18. Question 18. If A Host Is Not Able To Get The Mac Address Of A Host, How It Knows About Its Ip Address?

      Answer :

      A host will either use a static file like /etc/hosts or DNS protocol to get the IP address of another host.

    19. Question 19. What Will Happen If An Arp Reply Is Not Received For An Arp Request?

      Answer :

      If an ARP reply is not received, then that IP address cannot be resolved to an Ethernet address. Without a Ethernet address, the packets cannot be transmitted.

    20. Question 20. When Is An Entry Added To The Arp Cache?

      Answer :

      A new entry is added to the ARP cache when an IP address is successfully mapped to a MAC address. Usually, entries are added dynamically to the ARP cache. Static entries can also be added.

    21. Question 21. What Will Happen If A New Arp Request Packet Is Received, But The Mac Address To Ip Address Is Already Present In The Arp Cache?

      Answer :

      If a ARP request packet is received and the mapping already exists in the ARP cache, it will be overwritten with the values present in the request.

    22. Question 22. When Is An Entry Removed From An Arp Cache?

      Answer :

      An entry in an ARP cache is removed after a pre-determined timeout period (e.g. 20 minutes).

    23. Question 23. What Is The Size Of An Arp Request And Reply Packet?

      Answer :

      The size of an ARP request or reply packet is 28 bytes.

    24. Question 24. How To Differentiate Between A Arp Request Packet And A Arp Reply Packet, As The Ethernet Type Field Is Same On Both The Packets?

      Answer :

      An ARP request packet can be differentiated from an ARP reply packet using the 'operation' field in the ARP packet. For a ARP request it is 1 and for an ARP reply it is 2.

    25. Question 25. Why Is The Hardware Mac Address Present In Both The Ethernet Header And The Arp Packet (request And Reply)?

      Answer :

      The Ethernet header is processed by the data link driver and removed from the packet. When the ARP layer gets the packet, it needs to know the hardware and protocol addresses in order to update the table. That is why the hardware MAC address is present in both the Ethernet header and the ARP packet.

    26. Question 26. What Is Proxy Arp?

      Answer :

      Proxy ARP is the process in which one system responds to the ARP request for another system. For example, host A sends an ARP request to resolve the IP address of host B. Instead of Host B, Host C responds to this ARP request.

    27. Question 27. What Is The Use Of Proxy Arp?

      Answer :

      When routers receive ARP requests from one network for hosts on the network, they will respond with a ARP reply packet with their MAC address. For example, let us say host A is in one network, host B is in another network and router C connects these two networks. When host A sends an ARP request to resolve the IP address of host B, the router C receives this packet. The router C sends an ARP reply with its MAC address. So host A will send all the packets destined for host B to the router C.

      Router C will then forward those packets to host B. Proxy ARP is also used if a host in a network is not able to understand subnet addressing. For example, if host A and host B are actually in two different subnets, but host A cannot understand subnet addressing. So host A assumes that host B is present in the same network. In this case a router, host C, can use proxy ARP to route packets between host A and host B.

    28. Question 28. What Is Gratuitous Arp?

      Answer :

      When a host sends an ARP request to resolve its own IP address, it is called gratuitous ARP. In the ARP request packet, the source IP address and destination IP address are filled with the same source IP address itself. The destination MAC address is the Ethernet broadcast address (FF:FF:FF:FF:FF:FF).

    29. Question 29. What Is The Use Of Gratuitous Arp?

      Answer :

      Gratuitous ARP is used for the following:

      In a properly configured network, there will not be an ARP reply for a gratuitous ARP request. But if another host in the network is also configured with the same IP address as the source host, then the source host will get an ARP reply. In this way, a host can determine whether another host is also configured with its IP address.

      When the network interface card in a system is changed, the MAC address to its IP address mapping is changed. In this case, when the host is rebooted, it will send an ARP request packet for its own IP address. As this is a broadcast packet, all the hosts in the network will receive and process this packet. They will update their old mapping in the ARP cache with this new mapping.

    30. Question 30. What Is A Default Gateway? What Happens If I Don't Have One?

      Answer :

      In general, a gateway is a device on a network that acts as an entrance to another network. In more technical terms, a gateway is a routing device that knows how to pass traffic between different subnets and networks. A computer will know some routes (a route is the address of each node a packet must go through on the Internet to reach a specific destination), but not the routes to every address on the Internet. It won't even know all the routes on the nearest subnets. A gateway will not have this information either, but will at least know the addresses of other gateways it can hand the traffic off to. Your default gateway is on the same subnet as your computer, and is the gateway your computer relies on when it doesn't know how to route traffic.

      If you don’t have a gateway your network communication have no problem. But you cannot communicate with other networks. That means your packet will not reach other networks.

    31. Question 31. Can A Workstation Computer Be Configured To Browse The Internet And Yet Not Have A Default Gateway?

      Answer :

      No. Never. A work station computer can brows the Internet only if it has a default gateway.

    32. Question 32. What Is A Subnet?

      Answer :

      A subnet is a portion of a network that is logically isolated from other parts of the network. Usually it’s divided by a router.

    33. Question 33. What Is Apipa?

      Answer :

      APIPA stands for Automatic Private IP Addressing. When you configure your computer to obtain IP Address automatically and a DHCP server cannot be contacted, then the computer will automatically assign an IP address from a specific range (169.254.0.1 to 169.254.255.254). Then this network will be isolated from all networks. Because it has no a default gateway and any other configuration parameters.

    34. Question 34. What Is An Rfc?

      Answer :

      Short for Request for Comments, a series of notes about the Internet, started in 1969 (when the Internet was the ARPANET). An Internet Document can be submitted to the IETF by anyone, but the IETF decides if the document becomes an RFC. Eventually, if it gains enough interest, it may evolve into an Internet standard.

      Each RFC is designated by an RFC number. Once published, an RFC never changes. Modifications to an original RFC are assigned a new RFC number.

    35. Question 35. What Is Rfc 1918?

      Answer :

      RFC 1918, published in 1996, describe the reservation of Private IP address. . Private networks are segments of IP address space reserved by IANA for use within an organization. These addresses can be used by anyone without being officially assigned by a registry or an ISP. The three most popular blocks among RFC1918 addresses are 192.168/16, 10/8 and 172.16/12. That is 10.0.0.0 – 10.255.25.255, 172.16.0.0 – 172.31.255.255 and 192.168.0.0. – 192.168.255.255 The addresses in these blocks are called "private IP addresses" in the Internet vernacular.

    36. Question 36. What Are The Limitations Of Ipv4 Address Classes?

      Answer :

      The limitations of IPv4 address classes are:

      1. A large number of IP addresses are wasted because of using IP address classes.
      2. The routing tables will become large. A separate routing table entry is needed for each network resulting in a large number of routing table entries.

    37. Question 37. How A Large Number Of Ip Addresses Are Wasted Using Ipv4 Address Classes?

      Answer :

      If a network has slightly more number of hosts than a particular class, then it needs either two IP addresses of that class or the next class of IP address. For example, let use say a network has 300 hosts, this network needs either a single class B IP address or two class C IP addresses. If class B address is allocated to this network, as the number of hosts that can be defined in a class B network is (2^16 - 2), a large number of host IP addresses are wasted. If two class C IP addresses are allocated, as the number of networks that can be defined using a class C address is only (2^21), the number of available class C networks will quickly exhaust. Because of the above two reasons, a lot of IP addresses are wasted and also the available IP address space is rapidly reduced.

    38. Question 38. What Are The Possible Solutions To The Limitations Of Ip Addressing?

      Answer :

      The possible solutions to the limitation of IPv4 addressing are:

      1. IP version 6 (IPv6) or IP next generation (IPng). This is the latest version of IP. This solves a lot of problems in IPv4. This document doesn't discuss about IPv6.
      2. Classless Inter Domain Routing (CIDR).

    39. Question 39. What Is Cidr?

      Answer :

      Classless Inter Domain Routing (CIDR) is a method for assigning IP addresses without using the standard IP address classes like Class A, Class B or Class C. In CIDR, depending on the number of hosts present in a network, IP addresses are assigned.

    40. Question 40. Which Rfcs Discuss About Cidr?

      Answer :

      RFCs 1517, 1518, and 1519 discusses about CIDR.

    41. Question 41. What Is The Difference Between Classful Ip Addressing And Classless Ip Addressing?

      Answer :

      The difference between classful IP addressing and classless IP addressing is in selecting the number of bits used for the network ID portion of an IP address. In classful IP addressing, the network ID portion can take only the predefined number of bits 8, 16, or 24. In classless addressing, any number of bits can be assigned to the network ID.

    42. Question 42. How Is A Network Id Assigned In A Cidr Ip Address?

      Answer :

      In CIDR IP addressing, the first 'n' bits of an IP address are assigned to identify the network and the remaining bits are used to identify the host, where the value of 'n' may be between 1 to 31. The value of 'n' depends on the number of hosts in the network.

    43. Question 43. How Is An Ip Address Represented In Cidr Notation?

      Answer :

      In CIDR notation, an IP address is represented as A.B.C.D /n, where "/n" is called the IP prefix or network prefix. The IP prefix identifies the number of significant bits used to identify a network. For example, 192.9.205.22 /18 means, the first 18 bits are used to represent the network and the remaining 14 bits are used to identify hosts.

    44. Question 44. What Are The Advantages Of Cidr?

      Answer :

      The advantages of CIDR over the classful IP addressing are:

      1. CIDR can be used to effectively manage the available IP address space.
      2. CIDR can reduce the number of routing table entries.

    45. Question 45. How Two Systems In An Ethernet Network Communicate?

      Answer :

      In a Ethernet network, a system broadcasts the data using a Ethernet frame. The destination system is specified in the Ethernet frame using its Ethernet address. All the systems in the network listen for an Ethernet frame with their Ethernet address in it. When a system receives an Ethernet frame with its address in it, it processes the frame and sends it to the higher layers (like IP) for further processing.

    46. Question 46. What Is A "collision"?

      Answer :

      At any one instance, in an Ethernet network, only one device can transmit. If two devices transmit at the same instance, then the signals from both devices will collide and a "collision" will occur. When a "collision" occurs, the signals will get distorted and the frame will be lost. Collisions are very common in a Ethernet network.

    47. Question 47. How Is "collision" Handled In Ethernet Networks?

      Answer :

      Ethernet uses the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) media access control mechanism to detect and recover from a collision.

    48. Question 48. What Is Csma/cd?

      Answer :

      CSMA/CD is a media access control mechanism used in Ethernet to recover from frame collision. The following steps are followed to recover from a collision.

      • Step 1: Before an Ethernet device sends a frame on the Ethernet cable, it listens to find if another device is already transmitting a frame (Carrier Sense).
      • Step 2: Once the device finds that other devices are not transmitting any frame, it starts transmitting the frame. If two devices detect that the Ethernet cable is free at the same time, then both will start transmitting the frames (Multiple Access). This will result in collision.
      • Step 3: The Ethernet devices while transmitting the frames, also listen for the collision. (Collision Detect).
      • Step 4: If they detect a collision, both the devices stop sending the frame (back off).
      • Step 5: They retry the transmission after a logarithmic time-out period. This process is repeated till the frame is transmitted successfully, for a maximum of 16 times. The frame is discarded after the 16th retry.

    49. Question 49. What Is "late Collision"?

      Answer :

      An Ethernet device will detect a collision, while it is transmitting, only if the collision reaches it before it completes transmitting the entire frame. If the collision reaches the transmitter, after it completed sending the entire frame, then the transmitter will not detect the collision, it will assume the collision occurred because of some other frame. This is called "late collision". Late collision will occur, if the length of the Ethernet network segment is greater than the standard allowed length.

    50. Question 50. How "late Collision" Is Avoided In Ethernet?

      Answer :

      Late collision can be avoided, if the maximum length of the Ethernet network segment is restricted, such that if a collision occurs, it will reach the transmitter before the transmitter completed transmitting the entire frame. In a typical 10 Mbps network, the minimum length of an Ethernet frame is 576 bits (72 bytes) and the maximum length of a single Ethernet network segment is 2.5 kms.

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