🖧 Ilustrasi DNS Server dalam OSI Layer
DNS adalah layanan yang mengubah nama domain → alamat IP, dan bekerja menggunakan protokol UDP/TCP port 53.
Berikut diagram OSI secara vertikal:
+------------------------------------------------------------+
| Layer 7 |
| APPLICATION |
| - Proses DNS Query (A, AAAA, CNAME, MX, NS, PTR) |
| - Resolver pada OS/Browser mengirim permintaan DNS |
+------------------------------------------------------------+
| Layer 6 |
| PRESENTATION |
| - Format pesan DNS (encoding, struktur Query/Response) |
+------------------------------------------------------------+
| Layer 5 |
| SESSION |
| - Membuka sesi pertukaran data antara resolver & server |
+------------------------------------------------------------+
| Layer 4 |
| TRANSPORT |
| - UDP port 53 (query/respon kecil & cepat) |
| - TCP port 53 (zone transfer, respon besar >512 byte) |
+------------------------------------------------------------+
| Layer 3 |
| NETWORK |
| - Menggunakan IP (IPv4 / IPv6) |
| - Routing paket DNS menuju DNS server |
+------------------------------------------------------------+
| Layer 2 |
| DATA LINK |
| - Ethernet / Wi-Fi |
| - Mengemas paket IP menjadi frame, menggunakan MAC |
+------------------------------------------------------------+
| Layer 1 |
| PHYSICAL |
| - Kabel, serat optik, gelombang radio |
| - Sinyal real yang membawa data DNS |
+------------------------------------------------------------+
🔄 Alur Lengkap DNS Query & Response + OSI Layer
1. User mengetik domain (contoh: google.com)
📌 Browser meminta DNS resolver untuk mencari IP.
🎯 Layer bekerja: 7 – 5
2. DNS Query dikirim dari client ke DNS Server
Format: "What is the IP of google.com?"
🎯 Layer bekerja:
| Layer | Peran |
|---|---|
| L4 | UDP/TCP port 53 |
| L3 | IP tujuan = IP DNS Server |
| L2 | Frame ke MAC router |
| L1 | Sinyal listrik/gelombang dikirim |
3. DNS Server menerima query
Server memeriksa cache atau meneruskan (recursive/iterative).
🎯 Layer bekerja: 7 → 5 (logika aplikasi)
-
Parsing nama domain
-
Mencari record
-
Membangun respon DNS
4. DNS Response dikirim ke client
Contoh hasil: google.com → 142.250.4.78
🎯 Layer bekerja (kebalikan dari query):
-
L4 → UDP 53 → port random client
-
L3 → IP source = DNS server
-
L2 → Frame ke MAC client
-
L1 → Sinyal keluar
📘 Diagram Sederhana DNS + OSI
CLIENT PC/Laptop/HP
|
| DNS Query (UDP/TCP 53)
v
+--------------------------------------------------+
| OSI Layer |
| L7: DNS Application |
| L6: Format DNS Message |
| L5: Session Query |
| L4: UDP/TCP 53 |
| L3: IP → DNS Server |
| L2: Frame Ethernet/WiFi |
| L1: Kabel/Sinyal |
+--------------------------------------------------+
|
v
DNS SERVER
|
| DNS Response (IP Address)
v
CLIENT menerima alamat IP
CLIENT PC/Laptop/HP
|
| DNS Query (UDP/TCP 53)
v
+--------------------------------------------------+
| OSI Layer |
| L7: DNS Application |
| L6: Format DNS Message |
| L5: Session Query |
| L4: UDP/TCP 53 |
| L3: IP → DNS Server |
| L2: Frame Ethernet/WiFi |
| L1: Kabel/Sinyal |
+--------------------------------------------------+
|
v
DNS SERVER
|
| DNS Response (IP Address)
v
CLIENT menerima alamat IP
🏁 Kesimpulan
| OSI Layer | Peran dalam DNS |
|---|---|
| 7 | Proses query/respon DNS |
| 6 | Encoding & struktur data DNS |
| 5 | Membuka/menangani sesi DNS |
| 4 | UDP/TCP port 53 |
| 3 | Routing IP paket DNS |
| 2 | Frame Ethernet/WiFi |
| 1 | Transmisi sinyal |
🖧 Ilustrasi OSI Layer dalam Proses DHCP (Discover → Offer → Request → ACK)
+---------------------------------------------------------------+
| APLIKASI (Layer 7) |
+---------------------------------------------------------------+
| PRESENTATION (Layer 6) |
+---------------------------------------------------------------+
| SESSION (Layer 5) |
+---------------------------------------------------------------+
| DHCP CLIENT / SERVER MEMULAI KOMUNIKASI (DORA) |
+---------------------------------------------------------------+
| TRANSPORT (Layer 4) |
| - DHCP menggunakan UDP |
| - Client: port 68 |
| - Server: port 67 |
+---------------------------------------------------------------+
| NETWORK (Layer 3) |
| - Menggunakan IPv4 (0.0.0.0 → 255.255.255.255) |
| - Broadcast DHCP Discover |
+---------------------------------------------------------------+
| DATA LINK (Layer 2) |
| - Frame Ethernet |
| - Identifikasi MAC Address client |
+---------------------------------------------------------------+
| PHYSICAL (Layer 1) |
| - Kabel, sinyal listrik, gelombang, konektor |
+---------------------------------------------------------------+
🧩 Alur DORA (Discover, Offer, Request, Acknowledgement)
Dengan kaitannya ke OSI Layer
1. DHCP Discover (Client → Broadcast)
🔸 Tujuan: Client mencari DHCP Server.
OSI Layers yang bekerja
-
Layer 1 (Physical) → sinyal dikirim di kabel/wifi
-
Layer 2 (Data Link) → frame broadcast ke MAC FF:FF:FF:FF:FF:FF
-
Layer 3 (Network) → IP sumber 0.0.0.0 → broadcast 255.255.255.255
-
Layer 4 (Transport) → UDP 68 → 67
-
Layer 5-7 → membangun sesi DHCP client
2. DHCP Offer (Server → Client)
🔸 Tujuan: Server menawarkan alamat IP.
OSI Layers yang bekerja
-
Layer 1 → sinyal fisik
-
Layer 2 → frame dikembalikan ke MAC client
-
Layer 3 → broadcast/unicast tergantung konfigurasi
-
Layer 4 → UDP 67 → 68
-
Layer 5-7 → server menyiapkan konfigurasi (option, lease time)
3. DHCP Request (Client → Server)
🔸 Tujuan: Client memilih IP yang ditawarkan server.
OSI Layers yang bekerja
-
Layer 1-2 → broadcast lagi ke semua server
-
Layer 3 → broadcast IP 255.255.255.255
-
Layer 4 → UDP 68 → 67
-
Layer 5-7 → client mengunci pilihan server
4. DHCP ACK (Server → Client)
🔸 Tujuan: Mengonfirmasi bahwa IP resmi diberikan ke client.
OSI Layers yang bekerja
-
Layer 1 → sinyal listrik / gelombang
-
Layer 2 → frame ke MAC client
-
Layer 3 → IP unicast atau broadcast
-
Layer 4 → UDP 67 → 68
-
Layer 5-7 → konfigurasi final (gateway, DNS, lease time)
🎯 Diagram Ringkas DORA + OSI Layer
CLIENT DHCP SERVER
| |
|--- Discover --------------------------| L2 broadcast
|--- (L1–L4: UDP 68→67, L3 broadcast) --->|
| |
|<-- Offer -------------------------------| Server menawarkan IP
|<-- (L1–L4: UDP 67→68) ------------------|
| |
|--- Request ---------------------------->| Client memilih IP
|--- (L1–L4: UDP 68→67) ----------------->|
| |
|<-- ACK --------------------------------| IP diberikan
|<-- (L1–L4: UDP 67→68) ------------------|
🏁 Kesimpulan
DHCP bekerja pada berbagai layer OSI, terutama:
| OSI Layer | Fungsi dalam DHCP |
|---|---|
| L1 | Pengiriman sinyal fisik |
| L2 | Broadcast frame + MAC |
| L3 | IP 0.0.0.0 → 255.255.255.255 |
| L4 | UDP 67 ↔ 68 |
| L5–7 | Proses DORA, opsi DHCP, lease time |
0 Comments