You might be a network administrator if:

  1. What is the difference between layer 2 and layer 3 in the OSI model?
  2. What is the difference between a hub, switch, and router?
  3. What is a VLAN?
  4. What is the difference between TCP and UDP?
  5. How do you distinguish a DNS problem from a network problem?
  6. What is a runt, Giant, and collision?
  7. What is a broadcast storm?
  8. What is the purpose of VRRP?
  9. What is a VPN?
  10. What information about a peer would I need to establish a VPN?
  11. What is a full-class C in CIDR notation?
  12. What is a default route?
  13. What is a metric?
  14. What is a MAC address?
  15. What is ARP/RARP?
  16. Describe a TCP connection sequence
  17. What is MTU?
  18. What other TCP setting can you modify besides MTU to shorten packets?

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    13. What is the difference between layer 2 and layer 3 in the OSI model?

    Layer 2(Datalink Layer) is resposible for sending data b/w 2 node (within MAC resolution) and Flow, sequence control and error
    recovery by retransmission).

    while layer 3 (Network Layer) is transport the container of data with inter needs service of 3,4,5 layer to established session,authentication,packaging data,identification of data.

    14. What is the difference between a hub, switch, and router?
    A Hub is, in its simplest form, just like a mains multiplug unit. There is no intelligence or circuitry in it. More complex units may incorporate an amplifier or repeater. The network signal goes into one port and out of all the others. This is a Layer 1 device.
    A Switch has a small level of intelligence, in that it can open a message, check the IP address, and direct the message packets to the port on which the device with that IP address resides. It cannot modify IP addresses or see addresses outside of the range of the ‘home’ network. This is a Layer 2 device.
    A Router can read IP addresses, and direct the messages to another network with different IP addresses to the originating network. The Router software can build up an address table, so that it ‘knows’ where other devices are. This is a Layer 3 device.
    15. What is a VLAN?
    Virtual Local Area Network (VLAN) may be defined as a group of LANs that have different physical connections, but which communicate as if they are connected on a single network segment. VLANs were created because it increases overall network performance by grouping users and resources that communicate most frequently with each other. This means that the use of unicast or broadcast data transmission is limited, and traffic is reduced.
    16. What is the difference between TCP and UDP?
    TCP is a Transmission Control Protocol and UDP is a User Datagram Protocol.
    There are four major differences between UDP and TCP:
    1. TCP can establishes a Connection and UDP cannot.
    2. TCP provides a stream of unlimited length, UDP sends small packets.
    3. TCP gurantees that as long as you have a connection data sent will arrive at the destination, UDP provides not guarantee delivery.
    4.UDP is faster for sending small amounts of data since no connection setup is required, the data can be sent in less time then it takes for TCP to establish a connection.
    17. How do you distinguish a DNS problem from a network problem?
    If you are able to ping to a router or switch connected to DNS server but not able to ping DNS server. This is surely a problem with DNS….else its problem in the network. We can also use nslookup tool as well.
    18. What are a runt, Giant, and Late collision?
    A runt is a packet that fails to meet the minimum size standard. Usually below 64 bytes. Occurs as a result of a collision.

    A giant is a packet that exceeds the size standard for the medium usually grater then 1518 bytes . Caused by malfunctioning equipment on your network.

    Late collisions are packet collisions that occur after the window for a network collision closes.

    19. What is a broadcast storm?
    A state in which a message that has been broadcast across a network results in even more responses, and each response results in still more responses in a snowball effect. A severe broadcast storm can block all other network traffic, resulting in a network meltdown. Broadcast storms can usually be prevented by carefully configuring a network to block illegal broadcast messages.

    20. What is the purpose of VRRP?

    Virtual Router Redundancy Protocol (VRRP) is a non- proprietary redundancy protocol and it is used to avoid single point of failure of a gateway.

    21. What is a VPN?
    A Virtual Private Network (VPN) is a network technology that creates a secure network connection over a public network such as the Internet or a private network owned by a service provider.

    22. What is a default route?
    Default route is configured during the network configuration when the traffic comes to that network having no defined destination or route then that is sent on the default route.

    23. How do you set a default route on an IOS Cisco router?
    configure terminal
    ip route s0/0

    The ip route quad zero command will make anything that the router cannot find a route for go out the serial 0/0 interface.
    24. What is a metric?
    Metrics is a property of a route in computer networking, consisting of any value used by routing algorithms to determine whether one route should perform better than another.
    25. What is a MAC address?
    A MAC address, or Media Access Control address, is a 48- or 64-bit address associated with a network adapter. While IP addresses are associated with software, MAC addresses are linked to the hardware of network adapters. For this reason, the MAC address is sometimes called the hardware address, the burned-in address (BIA), or the physical address.
    26. What is ARP/RARP?
    ARP (Address Resolution Protocol) – The protocol that traces IP addresses to MAC addresses.
    RARP (Reverse Address Resolution Protocol) – The protocol within the TCP/IP stack that maps MAC addresses to IP addresses.
    27. Describe a TCP connection sequence.
    The connection establishment process actually accomplishes several things as it creates a connection suitable for data exchange:

    o Contact and Communication: The client and server make contact with each other and establish communication by sending each other messages. The server usually doesn’t even know what client it will be talking to before this point, so it discovers this during connection establishment.
    O Sequence Number Synchronization: Each device lets the other know what initial sequence number it wants to use for its first transmission.
    O Parameter Exchange: Certain parameters that control the operation of the TCP connection are exchanged by the two devices.

    28. What is MTU?
    Short for Maximum Transmission Unit, the largest physical packet size, measured in bytes that a network can transmit. Any messages larger than the MTU are divided into smaller packets before being sent.
    29. What other TCP setting can you modify besides MTU to shorten packets?
    Shorten the byte using ping command -l option

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