Computer Networks Chapter 4: Naming

Questions and Answers

To resolve names to the entity they refer to (correct)

To allocate IP addresses to entities

To provide a unique identifier for each entity

To manage user authentication

A physical device such as a printer or a host

Anything that can be operated on, including resources and objects (correct)

A unique identifier for a user or a process

A resource that offers an interface containing operations

A unique identifier for an entity

A string of bits or characters that refers to an entity (correct)

An IP address assigned to a host

A username or a password

Because the system itself is distributed Signup and view all the answers

Efficiency and scalability Signup and view all the answers

To make it easier and more flexible Signup and view all the answers

It refers to at most one entity and each entity is referred by at most one identifier Signup and view all the answers

A special entity that has a number of outgoing edges, each labeled with a name Signup and view all the answers

A sequence of labels corresponding to the edges of the path and the first node in the path Signup and view all the answers

A path name that starts from the root of the naming graph Signup and view all the answers

Study Notes

Names play an important role in distributed systems, enabling the sharing of resources, unique identification of entities, and reference to locations.
A naming system is necessary to resolve names to the entities they refer to, and its implementation is often distributed in nature.

An entity in a distributed system is anything that can be operated on, such as resources (hosts, printers, disks, files, objects, processes, users, etc.).
A name in a distributed system is a string of bits or characters used to refer to an entity.
An access point is an entity that provides an interface to operate on another entity, and its name is called an address (e.g., IP address and port number).
An entity can have multiple access points, and its access point may change over time (e.g., a mobile computer getting a new IP address).
An address is a special kind of name that refers to at most one entity and is unique to that entity, even when replicated.

A name can be location-independent, making it easier and more flexible to manage.
An identifier is a unique name that refers to at most one entity, is unique to that entity, and always refers to the same entity (never reused).
Examples of names, identifiers, and addresses include:
- Name of an FTP server (entity)
- URL of the FTP server
- Address of the FTP server (IP number: port number)

Names in a distributed system are organized into a name space, which is generally a labeled, directed graph with two types of nodes: leaf nodes and directory nodes.
Leaf nodes represent named entities and store information such as their addresses or state.
Directory nodes are special entities with outgoing edges labeled with names, storing directory tables that represent outgoing edges as pairs (edge label, node identifier).
Each node in a naming graph is an entity with an identifier, and a directory node stores a table of outgoing edges.
A path in a naming graph can be referred to by the sequence of labels corresponding to the edges of the path and the first node in the path, called a path name.
Path names can be absolute (starting from the root node) or relative, and may have multiple paths leading to the same node.