In tcp networking terminology. Organization of computer networks. Addressing. Defining the netmask

Analysis of the 12 tasks of the exam in 2016 in computer science from the demo. This is a knowledge quest basic principles organization and operation computer networks, addressing in the network (to be able to work with common automated information systems). This is a basic level of difficulty task. Estimated time to complete the task is 2 minutes.

Quest 12:

In TCP / IP networking terminology, a netmask refers to a binary number that indicates which part of a host's IP address refers to the address of a network, and which part to the address of the host itself on that network. Usually, the mask is written according to the same rules as the IP address - in the form of four bytes, and each byte is written as a decimal number. In this case, in the mask, first (in the most significant bits) there are ones, and then from some bit - zeros.
The network address is obtained by applying bitwise conjunction to the specified host IP address and mask.
For example, if the host IP address is 231.32.255.131 and the mask is 255.255.240.0, then the network address is 231.32.240.0.

For a host with an IP address of 111.81.208.27, the network address is 111.81.192.0. What is the smallest possible value of the third byte from the left of the mask? Write your answer as a decimal number.

Answer: ________

Analysis of the 12 tasks of the exam 2016:

To get the subnet address, you need to perform a bitwise conjunction (multiplication of binary digits) between the mask and the IP address.

Let's translate only the third byte of the IP address and the network address into the binary system, since, according to the condition of the task, we only need the third byte of the mask.

208 10 \u003d 11010000 2 - IP address
192 10 \u003d 11000000 2 - network address

Now getting the mask can be written like this:

11010000 - IP
xxxxxxxx - mask
———
11000000 - network address

By multiplying the bits of the IP address by the bits of the mask, we get the network address. Pay attention to the second from the right digit of the IP address and network address:

11 010000 - IP
x xxxxxxx - mask
———
11 000000 - network address

The second digit of the mask from the right cannot be zero, since in this case the network address must also be zero, which means that this x can only be one:

11 010000 - IP
x 1 xxxxxx - mask
———
11 000000 - network address

Now pay attention to the fourth bit from the right of the network address and IP, in IP it is 1, and in the network address - 0. That is, the fourth right bit of the mask cannot be one, since in this case the network address must also be one. It turns out that the fourth right bit of the mask is 0:

1101 0000 - IP
x1x 0 xxxx - mask
———
1100 0000 - network address

In the mask, at first (in the most significant bits) there are ones, and then from some bit - zeros, which means we can write the mask like this:

1101 0000 - IP
11x00000 - mask
———
110 00000 - network address

Last x can be either one or zero, but according to the condition of the assignment, we need the smallest byte of the mask, therefore, in the place x we put zero:

11010000 - IP
11000000 - mask
———
11000000 - network address

We translate 11000000 2 into the decimal number system and get the answer.

11000000 2 = 192 10

12.1 (ege.yandex.ru-1) In the terminology of TCP / IP networks, a network mask is a binary number that determines which part of the IP address of a network node refers to the address of the network, and which part to the address of the node itself in this network. Usually the mask is written according to the same rules as the IP address. The network address is obtained by applying bitwise conjunction to the specified host IP address and mask. Determine the network address from the specified host IP address and mask.

Host IP: 217.9.191.133

Mask: 255.255.192.0

Example.

Decision The network address has the form 217.9.X.0, where X is obtained by zeroing the 5 least significant bits in 191 (because 192 \u003d 255-63 \u003d 255 - (2 6 - 1) there are 6-1 \u003d 5 zero bits) ... Divide 191 by 64. Obviously, 191 \u003d 2 * 64 +63. Those. after zeroing the 6 least significant bits in the number 191, we get 2 * 64 \u003d 191-63 \u003d 128. Therefore, X \u003d 128.

Host address: 217.9.128.0

It remains to write letters instead of numbers, using the table from the condition: HBEA

Answer: HBEA

12.2 (ege.yandex.ru-2) In the terminology of TCP / IP networks, a network mask is a binary number that determines which part of the IP address of a network node refers to the network address, and which part to the address of the node itself in this network. Usually the mask is written according to the same rules as the IP address. The network address is obtained by applying bitwise conjunction to the specified host IP address and mask. Determine the network address from the specified host IP address and mask.

Host IP: 217.8.162.162

Mask: 255.255.224.0

When recording your answer, select four elements of the IP address from the numbers shown in the table and write down the corresponding letters in the desired order, without using periods.

Example.

Let the sought IP address 192.168.128.0, and given the table

In this case, the correct answer will be written as: HBAF

Decision The network address has the form 217.8.X.0, where X is obtained by zeroing the 4 least significant bits in the number 162 (because in the number 224 \u003d 255-31 \u003d 255 - (2 5 - 1) there are 5-1 \u003d 4 zero bits) ... We divide 162 by 32. We get: 162 \u003d 5 * 32 + 2 \u003d 160 + 2. Therefore, after zeroing the 5 least significant digits in the number 162, we get 5 * 32 \u003d 162-2 \u003d 160. That is, X \u003d 160.

Host address: 217.8.160.0

Answer: HBFA

12.3 (ege.yandex.ru-3) In the terminology of TCP / IP networks, a network mask is a binary number that determines which part of the IP address of a network node refers to the address of the network, and which part to the address of the node itself in this network. Usually the mask is written according to the same rules as the IP address. The network address is obtained by applying bitwise conjunction to the specified host IP address and mask. Determine the network address from the specified host IP address and mask.

Host IP address: 224.9.195.133

Mask: 255.255.192.0

When recording your answer, select four elements of the IP address from the numbers shown in the table and write down the corresponding letters in the desired order, without using periods.

Let the sought IP address 192.168.128.0, and given the table

In this case, the correct answer will be written as: HBAF

DecisionThe network address has the form 224.9.X.0, where X is obtained by zeroing the 5 least significant bits in the number 195 (because there are 6-1 \u003d 5 zero bits in the number 192 \u003d 255-63 \u003d 255 - (2 6 - 1)) ... Let's find the remainder of dividing 195 by 64 - this will show how much the number 195 will decrease when the 5 least significant digits are cleared. Can be divided with the remainder:

195: 64 \u003d 3 (3 rest). You can, without dividing, figure out that, since 192 is divisible by 64, the remainder will be 3. Thus, after zeroing the 5 least significant bits in the number 195, we will get 165-3 \u003d 3 * 64 \u003d 192. That is, X \u003d 192.

Host address: 224.9.192.0

It remains to write letters instead of the values \u200b\u200bof numbers, using the table from the problem statement.

Answer: HBFA

12.4 (ege.yandex.ru-4) In the terminology of TCP / IP networks, a network mask is a binary number that determines which part of the IP address of a network node refers to the network address, and which part to the address of the node itself in this network. Usually the mask is written according to the same rules as the IP address. The network address is obtained by applying bitwise conjunction to the specified host IP address and mask. Determine the network address from the specified host IP address and mask.

Host IP address: 224.12.78.162

Mask: 255.255.224.0

When recording your answer, select four elements of the IP address from the numbers shown in the table and write down the corresponding letters in the desired order, without using periods.

In this case, the correct answer will be written as: HBAF

DecisionThe network address has the form 224.12.X.0, where X is obtained by zeroing the 4 least significant bits in the number 78 (because in the binary notation of the number 224 \u003d 255-31 \u003d 255 - (2 5 - 1) there are 5-1 \u003d 4 zero discharges). Find the remainder of dividing 78 by 32 - this will show how much the number 78 will decrease when the 4 least significant digits are zeroed. When dividing we get: 78: 32 \u003d 2 (14 rest), i.e. 78 \u003d 2 * 32 + 14. Thus, after zeroing the 4 least significant bits in the binary notation of the number 78, we get 78 - 14 \u003d 2 * 32 \u003d 64. That is, X \u003d 64.

Host address: 224.12.64.0

It remains to write letters instead of the values \u200b\u200bof numbers, using the table from the problem statement.

Answer: GBCA

12.5 (ege.yandex.ru-5) In the terminology of TCP / IP networks, a network mask is a binary number that determines which part of the IP address of a network node refers to the address of the network, and which part to the address of the node itself in this network. Usually the mask is written according to the same rules as the IP address. The network address is obtained by applying bitwise conjunction to the given host IP address and mask. Determine the network address from the specified host IP address and mask.

Host IP address: 224.8.230.162

Mask: 255.255.224.0

When recording your answer, select four elements of the IP address from the numbers shown in the table and write down the corresponding letters in the desired order, without using periods.

Let the sought IP address 192.168.128.0, and given the table

In this case, the correct answer will be written as: HBAF

DecisionThe network address has the form 224.8.X.0, where X is obtained by zeroing the 4 least significant bits in the number 230 (because in the binary notation of the number 224 \u003d 255-31 \u003d 255 - (2 5 - 1) there are 5-1 \u003d 4 zero discharges). Find the remainder of dividing 230 by 32 - this will show how much the number 230 will decrease when the 4 least significant digits are cleared. When dividing, we get: 230: 32 \u003d 7 (6 rest), i.e. 230 \u003d 7 * 32 + 6. Thus, after zeroing the 4 least significant bits in the binary notation of the number 230, we get 230 - 6 \u003d 7 * 32 \u003d 224. That is, X \u003d 224.

Check 224 = 128+64+32 = 2 7 + 2 6 + 2 5 = 1110 0000 2 230 = 224+6 = 224+4+2 = 2 7 + 2 6 + 2 5 + 2 2 + 2 1 = 1110 0110 2

Let's perform a bitwise conjunction:

1110 0000 2 1110 0110 2 --------------------- 1110 0000 2 = 224

Host address: 224.8.224.0

It remains to write letters instead of the values \u200b\u200bof numbers, using the table from the problem statement.

Answer: DADH

Comment. You can find the remainder of dividing 230 by 32 without performing division. It is enough to notice that (1) 224 is divisible by 32 and (2) 230 - 224 \u003d 6< 32. Поэтому остаток от деления 230 на 32 равен 6, а X = 224.

Other solutions, including those recorded in more detail, are discussed at. If something is not clear, it is useful to look

In TCP / IP networking terminology, a netmask is a binary number that indicates how much of a host's IP address refers to a network address, and

which one - to the address of a node in this network. The network address is obtained by applying a bitwise conjunction to a given network address and its mask. Using the specified network IP address and mask, determine the network address:

Information that is essential and important at the moment is called: 1) complete; 2) useful; 3) relevant; 4) reliable. 2. Human tactile information

receives through: 1) special devices; 2) organs of touch; 3) hearing organs; 4) thermometer. 3. An example text information can serve: 1) multiplication table on the cover of a school notebook; 2) illustration in the book; 3) the rule in the native language textbook; 4) photography; 4. Translation of text from English into Russian can be called: 1) the process of storing information; 2) the process of obtaining information; 3) the process of information protection; 4) the process of information processing. 5. Exchange of information is: 1) doing homework; 2) watching a TV program; 3) observation of the behavior of fish in the aquarium; 4) talking on the phone. 6. The number system is: 1) a sign system in which numbers are written according to certain rules using symbols (numbers) of a certain alphabet; 2) an arbitrary sequence of numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; 3) the sequence of digits 0, 1 is infinite; 4) a set of natural numbers and signs of arithmetic operations. 7. The binary number 100012 corresponds to the decimal number: 1) 1110 2) 1710 3) 25610 4) 100110 8. The number 2410 corresponds to the number: 1) 1816 2) ВF16 3) 2016 4) 1011016 9. The unit of information is taken as: 1) 1 byte; 2) 1 bit; 3) 1 baud; 4) 1 cm. 10. Which of the devices is intended for information input: 1) processor; 2) printer; 3) keyboard; 4) monitor. eleven. Computer viruses: 1) arise due to failures in the computer hardware; 2) are of biological origin; 3) created by people specifically to damage PCs; 4) are the result of errors in operating system... 12. An algorithm is: 1) rules for performing certain actions; 2) a set of commands for the computer; 3) protocol for computer network; 4) a description of the sequence of actions, the strict execution of which leads to the solution of the problem in a finite number of steps. 13. The property of the algorithm, which consists in the absence of errors, the algorithm must lead to the correct result for all admissible input values, is called: 1) efficiency; 2) mass character; 3) discreteness; 4) limb. 14. The property of an algorithm, that the same algorithm can be used with different input data, is called: 1) efficiency; 2) mass character; 3) limb; 4) determinism. 15. Text editor - a program designed for: 1) creating, editing and formatting text information; 2) working with images in the process of creating game programs; 3) management of PC resources when creating documents; 4) automatic translation from symbolic languages \u200b\u200binto machine codes. 16. The main functions of a text editor include: 1) copying, moving, destroying and sorting text fragments; 2) creation, editing, saving and printing of texts; 3) strict adherence to spelling; 4) automatic processing of information presented in text files. 17. A cursor is: 1) a text input device; 2) a key on the keyboard; 3) the smallest display element on the screen; 4) a mark on the monitor screen indicating the position at which the text entered from the keyboard will be displayed. 18. Text formatting is: 1) the process of making changes to the existing text; 2) the procedure for saving text on disk in the form text file; 3) the process of transferring text information over a computer network; 4) a procedure for reading a previously created text from an external storage device. 19. Text typed in text editor, is stored on an external storage device: 1) as a file; 2) encoding tables; 3) catalog; 4) directories. 20. One of the main functions of the graphic editor is: 1) image input; 2) storage of the image code; 3) creating images; 4) viewing the output of the contents of the video memory. 21. The elementary object used in the raster graphics editor is: 1) screen point (pixel); 2) rectangle; 3) circle; 4) a palette of colors. 22. A spreadsheet is: 1) an application program designed to process data structured in the form of a table; 2) an application program for image processing; 3) a PC device that manages its resources in the process of processing data in tabular form; 4) a system program that manages PC resources when processing tables. 23. A spreadsheet is: 1) a set of numbered lines and columns named in the Latin alphabet; 2) a set of rows and columns named by letters of the Latin alphabet; 3) a set of numbered rows and columns; 4) a set of rows and columns, named by the user in an arbitrary way. 24. Select the correct formula entry for the spreadsheet: 1) C3 + 4 * E 2) C3 \u003d C1 + 2 * C2 3) A5B5 + 23 4) \u003d A2 * A3-A4

Annual test work, please help !!!

1) In the global computer network, the IP protocol provides:
a) Transfer of information to a given address
b) Partition transferred file into parts
c) Receiving mail messages
e) transmission of mail messages
2) The process of building models is
a) Modeling
b) construction
c) experimentation
e) design
3) Address is set email Online: Enter the name of the email owner.
a) rambler.spb.ru
b) klero
c) rambler
e) ru
4) HTML is
a) Tool for creating web pages
b) programming system
c) graphic editor
e) expert system
Thank you in advance!!)))

Please do those who know !!! ten . Indicate the numbers of the main devices that are included in the personal computer:

1) system unit 2) printer 3) monitor 4) keyboard.

11. What are the main components of the computer located in system unit?

1) monitor 2) floppy drive 3) motherboard 4) manipulator "mouse"

5) power supply.

12 Determine which category of PC software the described programs belong to:

1) perform various auxiliary functions;

2) ensure the performance of the work necessary for users: editing of texts; drawing pictures, etc .;

3) provide the creation of new programs for the computer.

1. Programming systems 2. System programs 3. Application programs

13. Choose which two tasks the OS should solve:

1) Distribute the time spent on the computer for each user.

2) Organize user interface.

3) Carry out preventive maintenance of equipment.

4) Organize joint work all nodes of the computer and perform the duties of the dispatcher of the computing process.

14. How can you define single-user and multi-user OS:

1) by the number of simultaneously solved tasks;

2) by the number of users;

3) by the number of processors.

15. Each file recorded on the disk has a designation consisting of two parts:

1) name and extension; 2) name and date of creation;

3) name and length; 4) file name and disk name.

16. Select the filenames containing programs ready to run:

1) mas.he; 2) mass txt; 3) mc.doc; 4) mc.bas; 5) mac.com.

17 . Local network is:

1) a computer network operating within one region;

2) a computer network operating within one country;

3) a computer network operating within the same institution.

18 . To create a local network, you need:

1) network card, modem, network cable, network software;

2) network card, network cable, network software;

3) network card, network cable, server.

19 . Specify the types of local network:

1) Server-based, Linear Bus, Ring;

2) star, linear bus, annular;

3) peer-to-peer, linear bus, ring;

20 . Information is transmitted at a speed of 2.5 Kbytes / s. How much information will be transmitted in 20 minutes? Record the result in megabytes.

21 . Hypertext ViewerWWW:

1) browser; 2) protocol; 3) server; 4) HTML;

Answer at least what you know: Questions in a crossword: Questions in a crossword:

1. A computer network that unites many local area networks... (10 letters)
2. Highly professional programmer. (5 letters)
3. Computer of the network subscriber. (8 letters)
4. A method of organizing textual information, within which semantic links are established. (10 letters)
5. Exchange of information on the global computer network. (As many as 16 letters!)

In TCP / IP networking terminology, a netmask is a binary number that indicates how much of a host's IP address refers to a network address, and

which one - to the address of a node in this network. The network address is obtained by applying a bitwise conjunction to a given network address and its mask. Using the specified network IP address and mask, determine the network address:

Information that is essential and important at the moment is called: 1) complete; 2) useful; 3) relevant; 4) reliable. 2. Human tactile information

receives through: 1) special devices; 2) organs of touch; 3) hearing organs; 4) thermometer. 3. An example of textual information is: 1) the multiplication table on the cover of a school notebook; 2) illustration in the book; 3) the rule in the native language textbook; 4) photography; 4. Translation of text from English into Russian can be called: 1) the process of storing information; 2) the process of obtaining information; 3) the process of information protection; 4) the process of information processing. 5. Exchange of information is: 1) doing homework; 2) watching a TV program; 3) observation of the behavior of fish in the aquarium; 4) talking on the phone. 6. The number system is: 1) a sign system in which numbers are written according to certain rules using symbols (numbers) of a certain alphabet; 2) an arbitrary sequence of numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; 3) the sequence of digits 0, 1 is infinite; 4) a set of natural numbers and signs of arithmetic operations. 7. The binary number 100012 corresponds to the decimal number: 1) 1110 2) 1710 3) 25610 4) 100110 8. The number 2410 corresponds to the number: 1) 1816 2) ВF16 3) 2016 4) 1011016 9. The unit of information is taken as: 1) 1 byte; 2) 1 bit; 3) 1 baud; 4) 1 cm. 10. Which of the devices is intended for entering information: 1) processor; 2) printer; 3) keyboard; 4) monitor. 11. Computer viruses: 1) occur due to failures in the hardware of the computer; 2) are of biological origin; 3) created by people specifically to damage PC; 4) are the result of errors in the operating system. 12. An algorithm is: 1) rules for performing certain actions; 2) a set of commands for the computer; 3) a protocol for a computer network; 4) a description of the sequence of actions, the strict execution of which leads to the solution of the problem in a finite number of steps. 13. The property of the algorithm, which consists in the absence of errors, the algorithm must lead to the correct result for all admissible input values, is called: 1) efficiency; 2) mass character; 3) discreteness; 4) limb. 14. The property of an algorithm, that the same algorithm can be used with different input data, is called: 1) efficiency; 2) mass character; 3) limb; 4) determinism. 15. Text editor - a program designed for: 1) creating, editing and formatting text information; 2) working with images in the process of creating game programs; 3) management of PC resources when creating documents; 4) automatic translation from symbolic languages \u200b\u200binto machine codes. 16. The main functions of a text editor include: 1) copying, moving, destroying and sorting text fragments; 2) creation, editing, saving and printing of texts; 3) strict adherence to spelling; 4) automatic processing of information presented in text files. 17. A cursor is: 1) a text input device; 2) a key on the keyboard; 3) the smallest display element on the screen; 4) a mark on the monitor screen indicating the position at which the text entered from the keyboard will be displayed. 18. Text formatting is: 1) the process of making changes to the existing text; 2) the procedure for saving text to disk as a text file; 3) the process of transmitting textual information over a computer network; 4) a procedure for reading a previously created text from an external storage device. 19. The text typed in a text editor is stored on an external storage device: 1) as a file; 2) encoding tables; 3) catalog; 4) directories. 20. One of the main functions of the graphic editor is: 1) image input; 2) storage of the image code; 3) creating images; 4) viewing the output of the contents of the video memory. 21. The elementary object used in the raster graphics editor is: 1) screen point (pixel); 2) rectangle; 3) circle; 4) a palette of colors. 22. A spreadsheet is: 1) an application program designed to process data structured in the form of a table; 2) an application program for image processing; 3) a PC device that manages its resources in the process of processing data in tabular form; 4) a system program that manages PC resources when processing tables. 23. A spreadsheet is: 1) a set of numbered lines and columns named by letters of the Latin alphabet; 2) a set of rows and columns named by letters of the Latin alphabet; 3) a set of numbered rows and columns; 4) a set of rows and columns, named by the user in an arbitrary way. 24. Select the correct formula entry for the spreadsheet: 1) C3 + 4 * E 2) C3 \u003d C1 + 2 * C2 3) A5B5 + 23 4) \u003d A2 * A3-A4

Annual test work, please help !!!

1) In the global computer network, the IP protocol provides:
a) Transfer of information to a given address
b) Splitting the transmitted file into parts
c) Receiving mail messages
e) transmission of mail messages
2) The process of building models is
a) Modeling
b) construction
c) experimentation
e) design
3) Internet e-mail address is set: Enter the name of the e-mail owner.
a) rambler.spb.ru
b) klero
c) rambler
e) ru
4) HTML is
a) Tool for creating web pages
b) programming system
c) graphic editor
e) expert system
Thank you in advance!!)))

Please do those who know !!! ten . Indicate the numbers of the main devices that are included in the personal computer:

1) system unit 2) printer 3) monitor 4) keyboard.

11. What are the main components of the computer located in the system unit?

1) monitor 2) floppy drive 3) motherboard 4) mouse

5) power supply.

12 Determine which category of PC software the described programs belong to:

1) perform various auxiliary functions;

2) ensure the performance of the work necessary for users: editing of texts; drawing pictures, etc .;

3) provide the creation of new programs for the computer.

1. Programming systems 2. System programs 3. Application programs

13. Choose which two tasks the OS should solve:

1) Distribute the time spent on the computer for each user.

2) Organize the user interface.

3) Carry out preventive maintenance of equipment.

4) Organize the joint work of all nodes of the computer and perform the duties of the dispatcher of the computing process.

14. How can you define single-user and multi-user OS:

1) by the number of simultaneously solved tasks;

2) by the number of users;

3) by the number of processors.

15. Each file recorded on the disk has a designation consisting of two parts:

1) name and extension; 2) name and date of creation;

3) name and length; 4) file name and disk name.

16. Select the filenames containing programs ready to run:

1) mas.he; 2) mass txt; 3) mc.doc; 4) mc.bas; 5) mac.com.

17 . Local network is:

1) a computer network operating within one region;

2) a computer network operating within one country;

3) a computer network operating within the same institution.

18 . To create a local network, you need:

1) network card, modem, network cable, network software;

2) network card, network cable, network software;

3) network card, network cable, server.

19 . Specify the types of local network:

1) Server-based, Linear Bus, Ring;

2) star, linear bus, annular;

3) peer-to-peer, linear bus, ring;

20 . Information is transmitted at a speed of 2.5 Kbytes / s. How much information will be transmitted in 20 minutes? Record the result in megabytes.

21 . Hypertext ViewerWWW:

1) browser; 2) protocol; 3) server; 4) HTML;

Answer at least what you know: Questions in a crossword: Questions in a crossword:

1. A computer network that unites many local networks. (10 letters)
2. Highly professional programmer. (5 letters)
3. Computer of the network subscriber. (8 letters)
4. A method of organizing textual information, within which semantic links are established. (10 letters)
5. Exchange of information on the global computer network. (As many as 16 letters!)

Author details

Fishing Natalia Mikhailovna

Place of work, position:

Secondary school № 4 named after the hero of the Soviet Union I.S. Khomenko, teacher

Khabarovsk region

Resource characteristics

Education levels:

Basic general education

Education levels:

Secondary (complete) general education

Class (s):

Class (s):

Class (s):

Item (s):

Informatics and ICT

The target audience:

Student (student)

Resource type:

Didactic material

Brief description of the resource:

Preparation for the Unified State Exam 2012. Assignments В11 on the topic: Terminology of TCP / IP networks

TCP / IP network terminology

Task B11

Preparation for the exam 2012

Subnet maskis called a 32-bit binary number that defines what part of a computer's IP address belongs to a network address, a which part of the IP address defines the computer's subnet address. In subnet mask the most significant bits set aside in the computer's IP address for the network address are 1; the least significant bits set aside in the computer's IP address for the computer's subnet address are 0... For example, the subnet mask might look like this:

11111111 11111111 111 00000 00000000 (255.255.224.0)

It means that 19 the most significant bits in the IP address contains the network address, the remaining 13 the least significant bits contain the address of the computer on the network.

Example 1

Let's find the network address, knowing the IP address (192.168.1.2) and the subnet mask (255.255.255.0). To do this, you need to apply to them the operation of bitwise conjunction (logical AND).

For this, we translate into a binary number system.

IP address: 11000000 10101000 00000001 00000010 (192.168.1.2)

Subnet mask:11111111 11111111 11111111 00000000 (255.255.255.0)

Network address: 11000000 10101000 00000001 00000000 (192.168.1.0)

Example 2

Using the specified network IP address and mask, determine the network address:

IP-address: 10.8.248.131 Mask: 255.255.224.0

Decision

In subnet mask the most significant bits set aside in the computer's IP address for network addresseshave value 1; least significant bits set aside in the computer's IP address for computer addresses in a subnet, have a value of 0

11111111 11111111 111 00000 00000000 (255.255.224.0)

This means that the 19 most significant bits in the IP address contain the network address, the remaining 13 least significant bits contain the address of the computer on the network. If the subnet mask is 255.255.255.240

let's perform a bitwise conjunction between these numbers -; mask 224 \u003d 11100000 2 indicates that the first three bits of the corresponding number in the IP address refer to the network number, and the remaining 5 to the host address:

248 = 11111000 2

224 = 11100000 2

so the network number part is 224 \u003d 11100000 2 and the node number is

X= 11000 2 = 24.

thus the complete network address is

Answer:10.8.224.0

AT 11 (DEMO2012

In the terminology of TCP / IP networks, a subnet mask is a 32-bit binary number that determines which digits of a computer's IP address are common to the entire subnet - in these digits the mask is 1. Usually masks are written in the form of four decimal numbers - according to the same rules as IP addresses. For some subnet, the mask is 255.255.252.0. How many different computer addresses does this mask theoretically allow? Note. In practice, not all of these addresses are used. For example, as a rule, IP addresses are not used, in decimal representation of which the last (rightmost) number is 0.

Decision

255.255.252.0.

11111111 11111111 111111 00 00000000

Q= 2 L

Q - the number of different words

L - word length

2 10 \u003d 1024 addresses

Answer: 1024

Example 3

If the subnet mask is 255.255.255.240 and the IP address of the computer on the network is 162.198.0.44, then the serial number of the computer on the network is _____

Decision:

It must be remembered that each part in the IP address (and in the mask) is an eight-bit binary number, that is, a decimal number from 0 to 255 (therefore, each part of the address and mask is called octet)

the first three numbers in the mask are 255, in the binary system it is 8 units, so the first three numbers of the computer's IP address entirely refer to the network number

for the last number (octet), the mask and the corresponding last part of the IP address are equal

240 = 11110000 2

44 = 00101100 2

above, the zero bits of the mask and the corresponding bits of the IP address, which determine the number of the computer on the network, are highlighted in blue: 1100 2 = 12

Answer: 12.

Do it yourself

1. If the subnet mask is 255.255.240.0 and the IP address of the computer on the network is 162.198.75.44, then the serial number of the computer on the network is _______