1️⃣ What is Azure Traffic Manager?¶

Azure Traffic Manager is a DNS-based global traffic routing service from Microsoft Azure.

👉 It does not sit in the data path 👉 It answers DNS queries based on routing rules

This makes it:

Extremely fast
Highly available
Perfect for multi-region failover

2️⃣ When to Use Traffic Manager¶

Use Traffic Manager when you need:

✅ Regional failover ✅ Multi-region active-passive ✅ Disaster recovery (DR) ✅ Global users

🚫 Not for:

Path-based routing
SSL termination
WAF

(That’s App Gateway / Front Door)

3️⃣ Routing Methods (Quick Overview)¶

Routing Method	Use Case
Priority	Active-Passive failover
Weighted	Traffic split (canary)
Performance	Nearest region
Geographic	Country-based
MultiValue	Multiple healthy endpoints

👉 We focus on Priority routing here.

4️⃣ Architecture: Priority Routing (Active-Passive)¶

User
 ↓  DNS Query
Azure Traffic Manager
 ↓
Primary Endpoint (Region A)
 ↓ (if unhealthy)
Secondary Endpoint (Region B)

5️⃣ Prerequisites (Lab Setup)¶

You need two regional endpoints, for example:

Region 1 (Primary):
Azure Application Gateway / Load Balancer
Public IP or DNS
Region 2 (Secondary):
Same setup
Different region

Example:

eastus-app.example.com
westus-app.example.com

6️⃣ Step-by-Step: Create Traffic Manager Profile¶

🔧 Step 1: Create Traffic Manager¶

Azure Portal → Traffic Manager profiles → Create

Basics

Setting	Value
Routing method	Priority
Subscription	Your subscription
Resource group	Existing / New
Name	`tm-priority-demo`

🔧 Step 2: Configure DNS Settings¶

Traffic Manager gives you:

tm-priority-demo.trafficmanager.net

👉 This becomes the global entry point

7️⃣ Add Endpoints (Critical Step)¶

🔧 Step 3: Add Primary Endpoint¶

Traffic Manager → Endpoints → Add

Setting	Value
Type	Azure endpoint / External
Name	primary-eastus
Target	App Gateway / LB
Priority	1
Endpoint status	Enabled

🔧 Step 4: Add Secondary Endpoint¶

Setting	Value
Name	secondary-westus
Target	App Gateway / LB
Priority	2
Endpoint status	Enabled

📌 Lower number = higher priority

8️⃣ Configure Health Checks (Monitoring)¶

🔍 Step 5: Monitoring Settings¶

Traffic Manager → Configuration

Setting	Recommended
Protocol	HTTP
Port	80 or 443
Path	`/health`
Probe interval	30 seconds
Tolerated failures	3

👉 Traffic Manager uses this to decide failover

9️⃣ Create Health Endpoint on Backends¶

On each region, ensure:

curl http://<REGIONAL_ENDPOINT>/health

Returns:

200 OK

Example (Nginx):

location /health {
    return 200 "OK";
}

🔟 Test Priority Routing (Normal State)¶

🧪 Test 1: DNS Resolution¶

nslookup tm-priority-demo.trafficmanager.net

Result:

Resolves to Primary region IP

🧪 Test 2: Application Access¶

curl tm-priority-demo.trafficmanager.net

Response:

Hello from EAST US

✅ Traffic always goes to Priority 1

1️⃣1️⃣ Test Regional Failover (IMPORTANT)¶

Now simulate a real outage 🔥

🧪 Test 3: Break Primary Region¶

Options:

Stop backend service
Block port 80/443
Stop VM / App Gateway

Example:

sudo systemctl stop nginx

🧪 Test 4: Observe Failover¶

Wait:

~90 seconds (probe interval × tolerated failures)

Then:

nslookup tm-priority-demo.trafficmanager.net

Now resolves to:

Secondary region IP

Access app:

curl tm-priority-demo.trafficmanager.net

Response:

Hello from WEST US

✅ Regional failover successful

1️⃣2️⃣ Restore Primary (Failback)¶

Restart primary service:

sudo systemctl start nginx

After probes succeed:

Traffic automatically returns to Priority 1

🔁 This is automatic failback

1️⃣3️⃣ Key Characteristics (Interview Gold)¶

DNS-based → TTL matters
No packet inspection
Health probes decide routing
Works with any public endpoint
Global, highly available

1️⃣4️⃣ Common Mistakes¶

❌ No /health endpoint ❌ Long DNS TTL (slow failover) ❌ Assuming instant failover ❌ Expecting L7 features ❌ Using Traffic Manager for private endpoints

1️⃣5️⃣ Traffic Manager vs Front Door (Quick)¶

Feature	Traffic Manager	Front Door
Routing level	DNS	HTTP
WAF	❌	✅
SSL termination	❌	✅
Failover	✅	✅
Cost	Low	Higher

1️⃣6️⃣ Interview-Ready Explanation (30 Seconds)¶

Azure Traffic Manager is a DNS-based global traffic routing service. With priority routing, it enables active-passive regional failover by directing traffic to the highest-priority healthy endpoint based on health probes.

1️⃣7️⃣ Real-World Production Pattern¶

User
 ↓
Azure Traffic Manager (Priority)
 ↓
Region A (Primary)
 ↓ (fail)
Region B (Secondary)