A service that provides information about remote resources given a name.

Terminology

1. Pure names: pure - no internal information non-pure - contains information

IP address is non-pure name because it contains a location information (class, net id and host id)

1. Flat or hierarchical flat - all names directly comparable hierarchical - names interpreted in an environment

File systems

The inode is a data structure used to represent a filesystem object. Each inode stores the attributes and disk block location(s) of the filesystem object’s data.

• A hard link to a file will point to the place where the file is stored or the inode of that file.
• A symbolic (soft) link will point to the actual file itself. Because file “soft.txt” points to file “foo.txt” itself, if file “foo.txt” is deleted, then file “soft.txt” will have nothing to point to; it is also deleted.

DNS - Domain Name Service

The Domain Name System is a name service design whose central naming database is used across the Internet.

A DNS name consist of:

• a top-level domain: se
• a sequence of subdomains: kth
• possibly a host name: www

DNS architecture

Each server is an authoritative server for a zone; it holds the master record for the nodes below it. Authoritative servers also work as slave servers for other zones to provide redundancy.