Menene OSI da TCP/IP models?

Question

IT Interview Practice · Accepted Answer

Dukansu **layered models** ne da ke bayyana yadda ake tsara sadarwar hanyar sadarwa: kowane layer yana sarrafa abu ɗaya kuma yana magana kawai da layers da ke kai tsaye sama da ƙasa da shi. **OSI model** nassoshi ne na hankali mai layers 7; **TCP/IP model** shine model mai layers 4 da ainihin intanet ke gudana a kai. Suna daidaituwa da juna:

```text
   OSI (7 layers, conceptual)          TCP/IP (4 layers, practical)      Examples
 ┌──────────────────────────┐        ┌──────────────────────────┐
 │ 7 Application            │        │                          │
 │ 6 Presentation          ─┼──────▶ │ Application              │  HTTP, DNS, TLS
 │ 5 Session               ─┘        │                          │
 ├──────────────────────────┤        ├──────────────────────────┤
 │ 4 Transport              │──────▶ │ Transport                │  TCP, UDP
 ├──────────────────────────┤        ├──────────────────────────┤
 │ 3 Network                │──────▶ │ Internet                 │  IP, ICMP
 ├──────────────────────────┤        ├──────────────────────────┤
 │ 2 Data Link             ─┼──────▶ │ Link (Network Access)    │  Ethernet, Wi-Fi,
 │ 1 Physical              ─┘        │                          │  ARP, cables
 └──────────────────────────┘        └──────────────────────────┘
```

Mahimmancin ra'ayi shine **encapsulation**: yayin da bayanai ke gangarowa ƙasa da stack a bangaren mai aikawa, kowane layer yana nannaɗe shi da nasa header (HTTP payload → TCP segment → IP packet → Ethernet frame); a bangaren mai karɓa yana tafiya baya sama, kowane layer yana cire nasa header. Wannan shine dalilin da yasa za ka iya musanya Wi-Fi da Ethernet ba tare da canja code na HTTP ba — layers suna da 'yancin kai.

Ga masu shirye-shirye, layers da kake taɓawa kullum su ne **Application** (HTTP, DNS), **Transport** (TCP da UDP — ports, aminci), da **Internet** (adireshin IP, routing). Layers na link/physical na ƙasa OS da hardware ne ke sarrafa su.

## Me ya sa yake da muhimmanci

Masu hira suna amfani da wannan tambaya don duba ko kana tunani cikin **stack mai tsari** maimakon wani gungu marar tabbas na "hanyar sadarwa." Sanin wane layer ra'ayi ke rayuwa a kai — port shine Transport, adireshin IP shine Internet, certificate shine Application — yana bari ka yi tunani game da matsaloli daidai ka kuma sanya kowace sabuwar fasaha a kan taswira. Shi ne kuma ƙamus ɗin da aka raba wanda sauran hanyar sadarwa ke ginuwa a kai: TCP, IP, TLS, da load balancers duk ana bayyana su ta wane layer suke aiki a kai.

Me ya sa yake da muhimmanci

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