MODULE 4 Flashcards

1
Q

Name:

A

Denotation to an entity in a distributed system

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2
Q

Identifier:

A

A name with properties

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2
Q

Access point:

A

Entities named by means of an address

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3
Q

Pure name:

A

Random string that has no meaning and is only used for comparisons

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4
Q

Broadcasting:

A

Using an entity’s ID to request the entity to return its address

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4
Q

Identifier properties:

A
  • An identifier refers to only one entity
  • An entity can only be referred to by one identifier
  • An identifier always refers to the same entity
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4
Q

Chord organization:

A
  • Each node has a random identifier
  • Each entity has a unique key
  • An entity is assigned to the node with the smallest ID that is greater or equal to the entity’s key (succ(k))
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5
Q

ARP’s job:

A

Finding out the MAC address associated with an IP address

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5
Q

HLS stands for _____

A

Hierarchical Location Services

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5
Q

Geographical scalability problems require separate chain reduction mechanisms because:

A
  • Long chains aren’t fault tolerant
  • There’s an increased network latency at dereferencing
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5
Q

ARP stands for _____

A

Address Resolution Protocol

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6
Q

Chord:

A

Nodes organized in a ring where each node and entity have unique identifiers in order for nodes to store these entities using their identifiers

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6
Q

HLS organization:

A
  • Address of an entity is stored in a leaf or intermediate node
  • Intermediate nodes store a pointer to a child if the child’s subtree contains the entity’s address
  • Root knows all entities
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7
Q

HLS:

A

A search tree with networks divided into domains, and each domain is represented by a directory

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8
Q

HLS lookup operation:

A
  1. Start at local leaf
  2. If the node knows about the entity, follow it’s downward pointer, else go up
  3. Upward lookup stops at root
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8
Q

HLS insert operation:

A
  1. Keep forwarding request till a node that knows about the entity is reached
  2. Create a chain of pointers to the leaf
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9
Q

Self-certifying name:

A

Flat names for entities that include a derived value from the entity itself

9
Q

HLS scaling steps:

A
  1. Choose physical servers for the logical server per entity
  2. Map entities to physical servers in a way that distributes the load of records
10
Q

Approaches to trust that name-resolution returns what’s associated with a flat name:

A
  • Secure identifier-to-entity associations
  • Secure name-resolution process
11
Q

Naming graph:

A

A graph where leaves represent named entities

12
Q

Directory node:

A

An entity that refers to other nodes

13
Q

Mounting:

A

Associating a node identifier of another name space with a node in current name space

13
Q

Node attributes:

A
  • Entity type
  • Entity identifier
  • Entity address
  • Nicknames
13
Q

Directory node contains:

A
  • Table of (node identifier; edge label) pairs
  • Attributes
13
Q

Closure mechanism:

A

A mechanism that selects the context to start with for name resolution

14
Q

Edge label:

A

Incoming edges to nodes

14
Q

Foreign name space:

A

The name space that needs to be accessed for mounting

15
Q

Mount point:

A

The node in current name space for mounting

16
Q

Implicit location dependency:

A

Mapping nodes to servers that can be located anywhere

16
Q

Mounting point:

A

The node in foreign name space that continues the name resolution for mounting

17
Q

DNS stands for _____

A

Domain Name Service

18
Q

Requirements for mounting across a network:

A
  • Access protocol name
  • Server name
  • Mounting point name
18
Q

DNS:

A

Hierarchical name space with each node having exactly one edge label

19
Q

Domain:

A

Subtree

20
Q

Domain name:

A

A path name to the domain’s root

21
Q

Securing a DNS:

A

Grouping records of the same type into a signed set per zone

22
Q

Zone-signing key:

A

The public key of the secret key used for signing a set of records

23
Q

Process for trusting the signatures:

A
  1. Zone-signing keys are grouped into another set that is signed by another secret key
  2. Hash of key-signing key is signed by the parent zone
24
Q

Key-signing key:

A

The public key of the secret key used for signing a set of zone-signing keys

25
Q

LDAP stands for _____

A

Lightweight Directory Access Protocol

26
Q

Drawbacks of distributed index:

A
  • A query with n attributes requires contacting n servers
  • No support for range queries
27
Q

Space-filling curve steps:

A
  1. Map n-dimensional space of n attributes into a one dimension
  2. Hash values to distribute the 1-dimensional space among index servers