OSI Model

Dosto is post par main aapko OSI Model ke bare mai puri jankari dunga sabse pahle main apko bata raha hun ki OSi Model hai kya OSI ki full form open system interconnection hota hai. jab do user ke bach mai ya kisi website or user ke bich mai koi communication hota hai. jaise aap kisi website ko open kar rahe hain manlo Google.com to apke google.com open karne se lekar open hone tak ke bich mai jo processing hoti hai use hi OSI Model kaha jata hai vaise ab OSI Model ko TCP/IP Model mai change kar diya gaya hai uske bare mai hum agee janenge . ek normal user ko sirf itna hi malum hota hai ki usne website open ki or open ho gayi par bich mai process kya hota hai uske bare mai use jankari nahi hoti. paar ek ethical hacker bana hai to networking ki bahut jankari honi chahiye. OSI Model ki seven layers hoti hai . or ye reverse chalti hai user ke through jab kisi website ko open karne ki request send ki jati hai. jaise seven to one  or jab request website par ja rahi hoti hai tab ye one to seven chalti hai main aapko seven layers ki puri jankari de raha hun.

7. Application layer

6. Presentation layer

5. Session layer

4. Transport layer

3. Network layer

2. Data Link Layer

1. Physical layer

• Application layer⇒ Application layer par apke computer ke sabhi applicationas aaplication layer par chalti hai jaise aap chahe internet surfing kare ya koi software use kare koi game khele yeh sabhi chije application layer par hi work karti hai . application layer se hote hue apki request physical layer tak jati hai.

• Presentation  layer⇒ Presentation layer data ko "generi- fies" karta hai jaise aapne application layer par apne browser par google.com open kiya hai  aab computer ko google.com ka format nahi malum hai jasie google.com ek web page hai or web page html format mai hota hai to presentation layer par data ka format ko phchana jata hai. or sath hi presentation layer encryption service bhi provide karti hai jaise jo websites secure hoti hai https://www.google.com yeh chij bhi presentation layer par hi define hoti hai.

• Session layer⇒ Session layer ka kam kisi bhi appplication ko start karna or uska end karna hota hai jaise aapne apne browser mai ek tab par google.com  open kiya hua hai ek tab par microsoft.com open ki hai ek tab par facebook.com open ki hai to es chij ka dhyan ki sbhi webpages open ho or close ho session layaer par rakha jata hai. jaruri nahi ki web pages ho koi software bhi ho sakta hai. software ko start or end karna session layer ka kam hota hai. or application layer, presentation layer , session layer par jo kam hote hai sabhi operating system par hi ho jate hai. or baki bachi hui four layers network par work karti hai

• Transposrt layer⇒ Transport layer par yeh dekha jata hai ki data ko kaise bhejna hai reliable ya non-reliable matlab TCP ya UDP se bhejna hai reliable ka matlb hota hai ki data source computer se destination computer tak phch raha hai ya nahi sahi tarah se jaise manlo aapne server par 5 mb ki file ko upload karna hai to vo file 5 mb ki 5 parts mai divide ho jayegi 1 mb, 1 mb , 1 mb, 1 mb , 1 mb or apki file ke sabhi packets sahi tarike se server par upload hoge agr nahi hote manlo ek packet miss ho gya 1 mb ka to apka computer dubara usi 1 mb ke part ko upload karega upload hone par server se ek acknowledgment user tak ata hai file milne ka  non-reliable ka use real time applocation mai hota hai jaise voice over ip jaise televisions or data ko kis port se bhejna hai ye bhi Transport layer par hi define hota hai. jaise web request 80 ya 443 port no par jati hai.

•  Network layer⇒  Network layer par Logical Addressing hoti hai aap ise IP Addressing bhi keh sakte hai Network layer par apke computer ka IP address check hota hai or apne jaha requset send ki hai uska IP address bhi jana jata hai or apke computer se Destination tak pahuchne ke best path konsa hai yeh bhi Network layer par hi define hota hai.

•  Data Link layer⇒ Data Link layer pat Physical addressing hoti hai apke computer ke mac address ko define kiya jata hai or sath hi Data error-free send ho is bat ka dhyan bhi Data Link layer karti hai. jaise apka bheje hue data mai kisi tarah ki koi error na ho yeh Data Link layer par hi define hota hai.

• Physical layer⇒ Physical layer par apke computer ki cables work karti hai jaise apke computer mai jitni bhi cables hoti hai vo sabhi Physical layer par hi work karti hai or apka data zero or one ki format mai bhi Physical layer par hi convert ho jata hai. phir apka data zero or one ke format mai cables se flow karta hua apke Destination address tak pahuchta hai.

main ummed karta hu ki aapko OSI Model ke bare mai puri jankari mil gayi hogi. post achi lage to share kare dhanywad.

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