2. EDNS Client Subnet (ECS) in CDN solution
Speaker: Pham Tran Kim Chi 2

3. Agenda - What is EDNS Client Subnet (ECS)
- How is EDNS Client Subnet (ECS)
- EDNS Client Subnet in Vinadata CDN
- Lesson learned 3

4. Recursive DNS Request

5. Recursive Geo IP DNS Request

6. Recursive Geo IP DNS Request

7. Recursive Geo IP DNS Request

8. EDNS Client Subnet (ECS)

9. Include client subnet EDNS Client Subnet (ECS)
• RFC
• Extension Mechanisms for DNS (EDNS0) option that is in active use to
carry information about the network that originated a DNS query and the
network for which the subsequent response can be cached.
Include client subnet

10. EDNS Client Subnet (ECS)

11. Use of DNS servers in Việt Nam
• ISP DNS server
• Google DNS server
• Open DNS server
• Others

12. How CDN works • GEO IP • Multiple criteria • This is called mapping
• Anycast: the content is served from the location the request is received.
• DNS based: CDN decides where to best served content from based on DNS
resolver/ client subnet.
• Multiple criteria
• Latency
• Packet loss
• Throughput
• CPU load on server
• …….
• This is called mapping
• The better the mapping, the better the CDN.

13. CDN with Anycast

14. CDN with EDNS Client Subnet

15. EDNS Client Subnet in Vinadata CDN
• Client requests from Google DNS.
• Google DNS asks VNG authoritative DNS with client subnet
• VNG DNS lookup client subnet and answers with an optimal
server for Google DNS.
• Google DNS give answer for client.
• Client request content from the optimal server

16. Lesson Learned • Deployment concerns • Privacy concerns
• Customize DNS Software to support EDNS.
• Ask to be added in EDNS support list.
• Privacy concerns
• Network scanning.
• Security concerns
• DNS request increases.
• Cache pollution.

17. Thanks! Contact us: VINADATA JSC Helios Building, Quang Trung
Software City, Dist.12
Ho Chi Minh City,
Vietnam 17