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12 - Subnet Masking

 1. IP addresses are divided into two parts: the _____________________ in the high-order bits and the remaining bits called the ________________________ used for host numbering within a network.

  network number / host identifier (rest field)

  binary number /network number

  address space number /network number

  hexadecimal address number

 2. Interestingly, in the early stages of the development of the Internet Protocol, the network number was always the most significant eight bits. This method allowed for only _____________________

  256 networks and soon proved inadequate as additional networks developed.

  256 networks, which was a reasonable amount to support the growth of the internet

  512,000 networks, which was the original size of the internet.

  128 networks which was sufficient, taking scaling into consideration

 3. In 1981 the addressing specification was revised with the introduction of classful network architecture. This allowed for a _____________of individual network assignments.

  smaller and more refined number

  larger number

  identical number

  smaller and more secure number

 4. The diagram shows the physical topology of a LAN (IPV4) setup. In suggesting suitable IP addresses for Router A, 192.168.2.255 would .....
picture_of_network_subnet.png

  not be suitable, as the third octet should contain a '1' instead of a '2'

  be perfectly suitable as the numbers can range from 0 to 255 (not 256)

  not be suitable, as 255 is usually reserved as the 'broadcasting' address. 0 is also reserved

  not be suitable as the 192 should be a 193 to indicate a difference device on the subnet

 5. A subnet mask tells a computer _________________________ and which it needs to access via a router.

  which IP addresses it is able to reach directly

  which DNS server is active

  which IPS is funcitoning correctly to serve the internet

  None of the above

 6. The most recognizable subnet mask is 255.255.255.0. It's the default subnet mask used by most ...
residential_routers_subnet_most_common.png

  super computer routers

  large company routers

  standalone machine routers

  residential (home based) routers

 7. In a subnet mask, 255 means that ________________________________________

  part of the IP address is definitely not the same as the one on the host

  part of the IP address must be the same as the one on the host.

  None of the above

  part of the IP address is obsolete and is no longer needed

 8. In a subnet mask, a 0 means that part of the IP address can vary from the host, but can _______________________

  still be deleted/not used if the user so desires

  None of the above

  still be accessed directly

  not be accessed directly

 9. The MASK itself is a 32-bit number that is applied to an IP using a bitwise logical AND comparison to split the address into the _______________________________________

  network identifier and the host identifier

  DNS address and IP Host

  host identifier and port number

  network identifier and socket number

 10. This identical prefix for the IP addresses indicates that these hosts...
hostsonthenetwork.png

  are on the same DNS server

  are on the same network

  are not going to be able to connect to the internet correctly (as they are not unique)

  are not on the same network

 11. An example of a B class network with the IP address 138.96.0.0 with a corresponding 16-bit network notation would be written as:

  138.1.1.1/16

  138.96.0.0/16

  138.96.16.16.1.1.1

  138.0.0.0/1

 12. What is the value of the subnet mask in this example that works out the network address?
10000001 00111000 10111101  00101001  IP ADDRESS (129.56.189.41)
11111111 11111111 111100001 00000000  SUBNET MASK (_____________)
==================================================
10000001 00111000 10110000  00000000  = NETWORK ADDRESS

  256.266.266.000

  255.255.240.0

  256.256.120.0

  128.128.256.0

 13. What has been done in these examples to find the network address?
10000001 00111000 10111101  00101001  IP ADDRESS (129.56.189.41)
11111111 11111111 111100001 00000000  SUBNET MASK (_____________)
==================================================
10000001 00111000 10110000  00000000  = NETWORK ADDRESS
subnetmask_and_operation_carriedout.png

  a logical 'OR' comparison has been applied

  a logical 'AND' comparison has been applied

  a binary addition followed by a logical 'AND' has been applied

  a logical 'XOR + AND' comparison has been applied

 14. In this example the IP address 129.56.189.41 has a network address of ______________ with the remaining numbers being the usable host identifier.

  129.56.189.41

  189.41

  129.56

  56.189

 15. Subnet mask is a mask used to determine _________________________. An IP address has two components, the network address and the host address.

  what internet service provider an IP address belongs to

  what DNServer an IP address belongs to

  what subnet an IP address belongs to

  how the IP address can be best used to identify the individual using the device