Routing policies (simple, weighted, latency) in AWS - Step-by-Step Execution

Process Flow - Routing policies (simple, weighted, latency)

User DNS Request

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Check Routing Policy Type

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Simple

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User gets IP

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Connects

User DNS requests are routed based on the chosen policy: simple returns one IP, weighted distributes traffic by weights, latency returns the lowest latency IP.

Execution Sample

AWS

User requests DNS -> Check policy -> Return IP based on policy

Shows how DNS queries are answered differently by simple, weighted, and latency routing policies.

Process Table

Step	Routing Policy	Input Request	Decision Logic	Returned IP	Reason
1	Simple	Request for example.com	Return single IP	192.0.2.1	Simple policy returns fixed IP
2	Weighted	Request for example.com	Select IP based on weights (70% 192.0.2.1, 30% 192.0.2.2)	192.0.2.1	Weighted policy chooses IP with probability
3	Weighted	Request for example.com	Select IP based on weights	192.0.2.2	Weighted policy chooses IP with probability
4	Latency	Request for example.com	Measure latency to IPs, choose lowest	192.0.2.3	Latency policy returns IP with lowest latency
5	Latency	Request for example.com	Measure latency to IPs, choose lowest	192.0.2.4	Latency policy returns IP with lowest latency
6	-	-	-	-	End of routing decisions

💡 Routing ends after returning IP based on policy logic

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
Returned IP	None	192.0.2.1	192.0.2.1	192.0.2.2	192.0.2.3	192.0.2.4	Varies per request

Key Moments - 3 Insights

Why does weighted routing sometimes return different IPs for the same domain?

Because weighted routing distributes traffic based on assigned weights, so different requests can get different IPs as shown in steps 2 and 3.

How does latency routing decide which IP to return?

Latency routing measures network delay to each IP and returns the one with the lowest latency, as seen in steps 4 and 5.

Does simple routing ever change the returned IP?

No, simple routing always returns the same single IP, demonstrated in step 1.

Visual Quiz - 3 Questions

Look at the execution table, what IP does simple routing return at step 1?

A 192.0.2.2

B 192.0.2.1

C 192.0.2.3

D 192.0.2.4

💡 Hint

Check the 'Returned IP' column at step 1 in the execution_table.

At which steps does weighted routing return different IPs?

A Steps 1 and 2

B Steps 4 and 5

C Steps 2 and 3

D Steps 3 and 4

💡 Hint

Look at the 'Routing Policy' and 'Returned IP' columns for steps 2 and 3.

If latency to 192.0.2.3 increases, which IP might latency routing return instead?

A 192.0.2.4

B 192.0.2.2

C 192.0.2.1

D 192.0.2.5

💡 Hint

Latency routing picks the IP with lowest latency; see steps 4 and 5 for examples.

Concept Snapshot

Routing policies control how DNS answers return IPs:
- Simple: returns one fixed IP
- Weighted: distributes traffic by weights
- Latency: returns IP with lowest network delay
Choose policy based on traffic needs and performance.

Full Transcript

Routing policies in AWS DNS decide how user requests get IP addresses. Simple routing always returns the same IP. Weighted routing splits traffic among multiple IPs based on assigned weights, so different requests may get different IPs. Latency routing measures network delay and returns the IP with the lowest latency to improve performance. This visual shows step-by-step how each policy picks the IP to return for DNS queries.