What is the drawback to using the traditional approach of having a single, publicly accessible web server?
It creates performance bottlenecks, high latency for distant users, and a single point of failure.
What is a CDN?
A distributed network of servers that deliver content from locations closer to end users.
What are the six major challenges that Internet applications face?
- Peering point congestion
- Inefficient Routing Protocols
- Unreliable Networks
- Inefficient communication protocols
- Scalability
- Application limitations and slow rate of change adoption
What are the major shifts that have impacted the evolution of the Internet ecosystem?
- Large scale
- Topological flattening
Compare the ‘enter deep’ and ‘bring home’ approach to CDN server placement.
Bring Home embeds servers inside ISPs; Enter deep places large clusters at few major PoPs.
What is the role of DNS in the way CDN operates?
DNS maps users to nearby or optimal CDN servers.
What are the two main steps in CDN server selection?
Select a cluster and then select a server within that cluster.
What is the simplest approach to selecting a cluster? What are the limitations?
Geographic proximity
May not be best end-to-end performance
- protocol inefficiency
- congestion
What metrics could be considered when using measurements to select a cluster?
- minimum RTT
- delay
- available bandwidth
- combination
How are the metrics for cluster selection obtained?
- Measurements
- ping probing
- passive (i.e. existing session performance)
Explain the distributed system that uses a 2-layered system. What are the challenges?
- Layers
- Coarse-grained global layer
- Fine-grained per-client decision layer- Requires intentional sub-optimal clustering
What are the strategies for server selection? What are the limitations?
- Random
- Load balancing
- Content Mapping
What is consistent hashing? How does it work?
A hashing scheme that maps servers and objects onto a ring to minimize remapping when servers join/leave.
Why would a centralized design with a single DNS server not work?
It wouldn’t scale, would be a single point of failure, and would introduce high latency globally.
What are the main steps that a host takes to use DNS?
Query resolver, contact authoritative servers, receive response, and cache results.
What are the services offered by DNS apart from hostname resolution?
- Mail server/Host aliasing
- Load distribution
What is the structure of the DNS hierarchy? Why hierarchical?
Root → TLD → authoritative servers; hierarchy scales globally and distributes load.
What is the difference between iterative and recursive DNS queries?
Iterative returns referrals; recursive performs full lookup on behalf of the client.
What is DNS caching?
Storing DNS responses temporarily to reduce lookup latency and server load.
What is a DNS resource record?
A structured DNS database entry containing information about a domain.
What are the most common types of resource records?
A, CNAME, MX, NS
Describe the DNS message format.
- 12 bytes meta (including ID)
- Name, type fields for a query
- RRs in response to query
- Records for authoritative servers
- Additional info
What is IP Anycast?
route client to closest server (via BGP)
What is HTTP Redirection?
A technique where a server instructs a client to request content from a different URL or server.
1. Client sends GET request
2. Server responds with cod 3xx and new server name
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Module 1: Quiz10
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Module 1: Practice Quiz5
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Module 2: Quiz21
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Module 2: Practice Quiz4
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Module 3: Quiz21
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Module 3: Practice Quiz14
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Module 4: Quiz23
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Module 4: Practice Quiz21
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Module 5: Quiz13
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Module 5: Practice Quiz27
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Module 6: Quiz10
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Module 7: Practice Quiz18
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Module 7: Quiz13
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Module 8: Practice Quiz33
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Module 8: Quiz21
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Module 9: Practice Quiz24
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Module 9: Quiz16
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Module 10: Practice Quiz13
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Module 10: Quiz14
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Module 11: Practice Quiz25
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Module 11: Quiz15
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Module 12: Quiz12
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Module 7: AI11
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Module 8: AI18
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Module 9: AI23
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Module 10: AI23
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Module 11: AI28
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Module 12: AI24
