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Docker Networking: Bridge, Host और Custom Networks

By Ravindra Bagale, DevOps trainer · LinkedIn · Published: 28 October 2026 · Last updated: 28 October 2026

Custom bridge, नाम से बात, -p, stacks isolate।

Language: English · मराठी · हिंदी

Networks क्यों

नाम से न मिलने वाले containers Compose में उलझन।

Why: स्थिर DNS और isolation। What: bridge/host/custom/-p। How: labnet बनाएँ।

Example 1: List networks

Type this:

command -v docker >/dev/null && docker network ls || printf "%s\n" "NETWORK ID NAME DRIVER\n... bridge bridge\n... host host\n... none null"

You will see:

NETWORK ID NAME DRIVER
... bridge bridge
... host host
... none null

What it means: Every Docker engine starts with bridge, host, and none.

Example 2: Create a custom bridge

Type this:

command -v docker >/dev/null && docker network create labnet || printf "%s\n" "labnet"

You will see:

labnet

What it means: User-defined bridges provide automatic DNS between containers.

Example 3: Inspect the network

Type this:

command -v docker >/dev/null && docker network inspect labnet --format "{{.Name}} {{.Driver}}" || printf "%s\n" "labnet bridge"

You will see:

labnet bridge

What it means: Driver bridge is the usual choice for multi-container apps on one host.

Concept 1: Custom DNS

User-defined bridge नाम resolve करता है।

Why: api→db hostname। What: --network; Compose How: Multi-service के लिए।

Example 4: Attach by name (sketch)

Type this:

printf "%s\n" "docker run -d --name db --network labnet redis:7" "docker run -d --name api --network labnet myapi:1"

You will see:

docker run -d --name db --network labnet redis:7
docker run -d --name api --network labnet myapi:1

What it means: api can resolve host db on labnet.

Example 7: Compose networks

Type this:

printf "%s\n" "services:" "  api:" "    networks: [appnet]" "  db:" "    networks: [appnet]" "networks:" "  appnet:"

You will see:

services:
  api:
    networks: [appnet]
  db:
    networks: [appnet]
networks:
  appnet:

What it means: Compose creates the user-defined network for you.

Example 8: DNS test sketch

Type this:

printf "%s\n" "docker exec api ping -c1 db"

You will see:

docker exec api ping -c1 db

What it means: Name db works on custom networks; often fails on legacy default bridge without links.

Concept 2: Publish/host

-p लोगों के लिए; host mode दुर्लभ।

Why: सावधानी से expose। What: -p; ss How: Conflict जाँचें।

Example 5: Publish a port

Type this:

printf "%s\n" "docker run -d -p 8080:80 --name web nginx:alpine"

You will see:

docker run -d -p 8080:80 --name web nginx:alpine

What it means: -p host:container maps traffic into the container.

Example 6: Host network note

Type this:

printf "%s\n" "docker run --network host ... shares the host network namespace"

You will see:

docker run --network host ... shares the host network namespace

What it means: Useful for special cases; skips isolation — rare in shared EC2 labs.

Example 11: Port conflict tip

Type this:

printf "%s\n" "Bind for 0.0.0.0:8080 failed = something else uses 8080" "ss -lntp | grep 8080"

You will see:

Bind for 0.0.0.0:8080 failed = something else uses 8080
ss -lntp | grep 8080

What it means: Check the host before changing the app.

Concept 3: Isolate

एक app एक network।

Why: Blast radius कम। What: connect/disconnect How: Network card।

Example 9: Isolate two stacks

Type this:

printf "%s\n" "app1net for shop" "app2net for blog" "Do not share unless needed"

You will see:

app1net for shop
app2net for blog
Do not share unless needed

What it means: Isolation reduces blast radius — Accenture security reviews like this.

Example 10: Disconnect / connect

Type this:

printf "%s\n" "docker network connect labnet api" "docker network disconnect labnet api"

You will see:

docker network connect labnet api
docker network disconnect labnet api

What it means: Move running containers between networks when needed.

Example 12: Network card

Type this:

printf "%s\n" "1 custom bridge 2 same network names 3 -p for humans 4 isolate stacks"

You will see:

1 custom bridge 2 same network names 3 -p for humans 4 isolate stacks

What it means: Memorize for Docker networking interviews.

Network card

1 custom bridge 2 api+db 3 -p 4 isolate

Suppose: Shop Compose

appnet।

Suppose: Port busy

ss; दूसरा port।

Check yourself (quiz)

Custom → DNS → publish → isolate. Did you understand? Let us try it once more.