TU Wien:Verteilte Systeme VO (Dustdar)/Pruefung 2019-06-05
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In arbitrary order
Name a resource-oriented and a file-based Distributed System[Bearbeiten | Quelltext bearbeiten]
resource-oriented: GRID, cloud, P2P, MANET
file-based: NFS
Explain the differences between layered and event-based architecture[Bearbeiten | Quelltext bearbeiten]
A client wants to download links form a given list. Which design you would choose for the client implementation, and why? Single-thread, multithread, or multiprocessor[Bearbeiten | Quelltext bearbeiten]
Socket primitives. Sketch the connection steps (socket -> bind -> listen …)[Bearbeiten | Quelltext bearbeiten]
TCP-Handoff (sketch)[Bearbeiten | Quelltext bearbeiten]
Primary-based protocol (sketch). There were four replicas, and replica 4 was primary. The client writes x on replica 1[Bearbeiten | Quelltext bearbeiten]
Lamport logical sequence + formula[Bearbeiten | Quelltext bearbeiten]
Lease expiry models[Bearbeiten | Quelltext bearbeiten]
Age-based leases: An object that hasn't changed for a long time, will not change in the near future, so provide a long lasting lease.
Renewal frequency-based lease: The more often a client requests a specific object, the longer the expiration date for that client (for that object) will be.
State-based leases: The more loaded a server is, the shorter the expiration times become.
Write and read operations given for processes (the same example in the slides for causal consistency). Determine if sequential and causal consistencies are valid or invalid (true/false)[Bearbeiten | Quelltext bearbeiten]
Explanation of your choices above[Bearbeiten | Quelltext bearbeiten]
Protection domains[Bearbeiten | Quelltext bearbeiten]
Common Implementation of Protection Domains
- Groups: Users belong to a specific group, each has associated access rights.
- Roles: Don't differentiate between users, but only the roles they can play. Your role is determined at login time. Role changes are allowed.
Decreasing time to lookup users to group/role mapping
- Certificates: Users provide certificate which groups/role they belong to.
3 use cases for cloud computing[Bearbeiten | Quelltext bearbeiten]
- Demand for a service varies with time
- Demand is unknown in advance
- Batch analysis
Overprovisioning (sketch + explain)[Bearbeiten | Quelltext bearbeiten]
Explain 2 of 3 name resolution approaches[Bearbeiten | Quelltext bearbeiten]
Centralized mutual exclusion (sketch + explain)[Bearbeiten | Quelltext bearbeiten]
KDC diagram with ticket system given (the same example in the slides). Indicate where the ticket + session key is[Bearbeiten | Quelltext bearbeiten]
Failure masking by redundancy[Bearbeiten | Quelltext bearbeiten]
- Information Redundancy: Add extra information
- Time Redundancy: Repeat request
- Physical Redundancy: Add additional components
Stateful and Stateless Servers. Give an example where stateful server implementations make sense?[Bearbeiten | Quelltext bearbeiten]
Namespace + Name domain[Bearbeiten | Quelltext bearbeiten]
Name Space: Contains all valid names recognised and managed by a service.
- A valid name might not be bound to any entity
- Alias: A name refers to another name.
Naming Domain: A name space with a single administrative authority which manages names for the name space.