Misplaced Pages

#860139

78-417: Many kinds of operating systems implement ACLs or have a historical implementation; the first implementation of ACLs was in the filesystem of Multics in 1965. A filesystem ACL is a data structure (usually a table) containing entries that specify individual user or group rights to specific system objects such as programs, processes , or files. These entries are known as access-control entries (ACEs) in

156-508: A World Wide Web server, and mail.example.com could be an email server, each intended to perform only the implied function. Modern technology allows multiple physical servers with either different (cf. load balancing ) or even identical addresses (cf. anycast ) to serve a single hostname or domain name, or multiple domain names to be served by a single computer. The latter is very popular in Web hosting service centers, where service providers host

234-496: A host or other layer 3 , each with a list of hosts and/or networks permitted to use the service. Although it is additionally possible to configure access-control lists based on network domain names , this is a questionable idea because individual TCP , UDP , and ICMP headers do not contain domain names. Consequently, the device enforcing the access-control list must separately resolve names to numeric addresses. This presents an additional attack surface for an attacker who

312-523: A tree of domain names. Each node in the tree holds information associated with the domain name. The tree sub-divides into zones beginning at the DNS root zone . A domain name consists of one or more parts, technically called labels , that are conventionally concatenated, and delimited by dots, such as example.com . When the Domain Name System was devised in the 1980s, the domain name space

390-495: A FQDN ends in a dot ( . ) to denote the top of the DNS tree. Labels in the Domain Name System are case-insensitive , and may therefore be written in any desired capitalization method, but most commonly domain names are written in lowercase in technical contexts. A hostname is a domain name that has at least one associated IP address . Domain names serve to identify Internet resources, such as computers, networks, and services, with

468-695: A component in Uniform Resource Locators (URLs) for Internet resources such as websites (e.g., en.wikipedia.org). Domain names are also used as simple identification labels to indicate ownership or control of a resource. Such examples are the realm identifiers used in the Session Initiation Protocol (SIP), the Domain Keys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs). An important function of domain names

546-542: A database of artists and agents, chose whorepresents.com , which can be misread. In such situations, the proper meaning may be clarified by placement of hyphens when registering a domain name. For instance, Experts Exchange , a programmers' discussion site, used expertsexchange.com , but changed its domain name to experts-exchange.com . The domain name is a component of a uniform resource locator (URL) used to access websites , for example: A domain name may point to multiple IP addresses to provide server redundancy for

624-424: A device, device type, directory prefix, file path separator, or file type. File systems typically support organizing files into directories , also called folders , which segregate files into groups. This may be implemented by associating the file name with an index in a table of contents or an inode in a Unix-like file system. Directory structures may be flat (i.e. linear), or allow hierarchies by allowing

702-672: A directory to contain directories, called subdirectories. The first file system to support arbitrary hierarchies of directories was used in the Multics operating system. The native file systems of Unix-like systems also support arbitrary directory hierarchies, as do, Apple 's Hierarchical File System and its successor HFS+ in classic Mac OS , the FAT file system in MS-DOS 2.0 and later versions of MS-DOS and in Microsoft Windows ,

780-523: A domain name identifies a network domain or an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, or a server computer. Domain names are formed by the rules and procedures of the Domain Name System (DNS). Any name registered in the DNS is a domain name. Domain names are organized in subordinate levels ( subdomains ) of the DNS root domain, which

858-517: A domain name, the labels are separated by a full stop (period). Domain names are often seen in analogy to real estate in that domain names are foundations on which a website can be built, and the highest quality domain names, like sought-after real estate, tend to carry significant value, usually due to their online brand-building potential, use in advertising, search engine optimization , and many other criteria. A few companies have offered low-cost, below-cost or even free domain registration with

SECTION 10

#1732793551861

936-429: A few other alternative DNS root providers that try to compete or complement ICANN's role of domain name administration, however, most of them failed to receive wide recognition, and thus domain names offered by those alternative roots cannot be used universally on most other internet-connecting machines without additional dedicated configurations. In the process of registering a domain name and maintaining authority over

1014-527: A file system can be managed by the user via various utility programs. Domain name In the Internet , a domain name is a string that identifies a realm of administrative autonomy, authority or control. Domain names are often used to identify services provided through the Internet, such as websites , email services and more. Domain names are used in various networking contexts and for application-specific naming and addressing purposes. In general,

1092-443: A file system creates a file, it allocates space for data. Some file systems permit or require specifying an initial space allocation and subsequent incremental allocations as the file grows. To delete a file, the file system records that the file's space is free; available to use for another file. A local file system manages storage space to provide a level of reliability and efficiency. Generally, it allocates storage device space in

1170-422: A file system implementation. The physical file system layer provides relatively low-level access to a storage device (e.g. disk). It reads and writes data blocks , provides buffering and other memory management and controls placement of blocks in specific locations on the storage medium. This layer uses device drivers or channel I/O to drive the storage device. A file name , or filename , identifies

1248-417: A file to consuming applications and in some cases users. A file name is unique so that an application can refer to exactly one file for a particular name. If the file system supports directories, then generally file name uniqueness is enforced within the context of each directory. In other words, a storage can contain multiple files with the same name, but not in the same directory. Most file systems restrict

1326-706: A forked file system on the Macintosh, and Microsoft supports streams in NTFS. Some file systems maintain multiple past revisions of a file under a single file name; the file name by itself retrieves the most recent version, while prior saved version can be accessed using a special naming convention such as "filename;4" or "filename(-4)" to access the version four saves ago. See comparison of file systems#Metadata for details on which file systems support which kinds of metadata. A local file system tracks which areas of storage belong to which file and which are not being used. When

1404-477: A granular manner, usually multiple physical units (i.e. bytes ). For example, in Apple DOS of the early 1980s, 256-byte sectors on 140 kilobyte floppy disk used a track/sector map . The granular nature results in unused space, sometimes called slack space , for each file except for those that have the rare size that is a multiple of the granular allocation. For a 512-byte allocation, the average unused space

1482-473: A lack of response to a domain name query as an indication that the domain does not exist, and that the message can be treated as undeliverable. The original VeriSign implementation broke this assumption for mail, because it would always resolve an erroneous domain name to that of Site Finder. While VeriSign later changed Site Finder's behaviour with regard to email, there was still widespread protest about VeriSign's action being more in its financial interest than in

1560-453: A registrar does not confer any legal ownership of the domain name, only an exclusive right of use for a particular duration of time. The use of domain names in commerce may subject them to trademark law . The practice of using a simple memorable abstraction of a host's numerical address on a computer network dates back to the ARPANET era, before the advent of today's commercial Internet. In

1638-400: A set of special-use domain names. This list contains domain names such as example , local , localhost , and test . Other top-level domain names containing trade marks are registered for corporate use. Cases include brands such as BMW , Google , and Canon . Below the top-level domains in the domain name hierarchy are the second-level domain (SLD) names. These are the names directly to

SECTION 20

#1732793551861

1716-431: A stream of bytes . Typically, to read file data, a program provides a memory buffer and the file system retrieves data from the medium and then writes the data to the buffer. A write involves the program providing a buffer of bytes that the file system reads and then stores to the medium. Some file systems, or layers on top of a file system, allow a program to define a record so that a program can read and write data as

1794-585: A structure; not an unorganized sequence of bytes. If a fixed length record definition is used, then locating the n record can be calculated mathematically, which is relatively fast compared to parsing the data for record separators. An identification for each record, also known as a key, allows a program to read, write and update records without regard to their location in storage. Such storage requires managing blocks of media, usually separating key blocks and data blocks. Efficient algorithms can be developed with pyramid structures for locating records. Typically,

1872-559: A superset of both NT ACLs and POSIX draft ACLs. Samba supports saving the NT ACLs of SMB-shared files in many ways, one of which is as NFSv4-encoded ACLs. Microsoft 's Active Directory service implements an LDAP server that store and disseminate configuration information about users and computers in a domain. Active Directory extends the LDAP specification by adding the same type of access-control list mechanism as Windows NT uses for

1950-449: A text-based label that is easier to memorize than the numerical addresses used in the Internet protocols. A domain name may represent entire collections of such resources or individual instances. Individual Internet host computers use domain names as host identifiers, also called hostnames . The term hostname is also used for the leaf labels in the domain name system, usually without further subordinate domain name space. Hostnames appear as

2028-660: A unique identity. Organizations can choose a domain name that corresponds to their name, helping Internet users to reach them easily. A generic domain is a name that defines a general category, rather than a specific or personal instance, for example, the name of an industry, rather than a company name. Some examples of generic names are books.com , music.com , and travel.info . Companies have created brands based on generic names, and such generic domain names may be valuable. Domain names are often simply referred to as domains and domain name registrants are frequently referred to as domain owners , although domain name registration with

2106-432: A user's use of storage space. A file system typically ensures that stored data remains consistent in both normal operations as well as exceptional situations like: Recovery from exceptional situations may include updating metadata, directory entries and handling data that was buffered but not written to storage media. A file system might record events to allow analysis of issues such as: Many file systems access data as

2184-441: A variety of models adopted to recoup the costs to the provider. These usually require that domains be hosted on their website within a framework or portal that includes advertising wrapped around the domain holder's content, revenue from which allows the provider to recoup the costs. Domain registrations were free of charge when the DNS was new. A domain holder may provide an infinite number of subdomains in their domain. For example,

2262-469: Is sos.state.oh.us . 'sos' is said to be a sub-domain of 'state.oh.us', and 'state' a sub-domain of 'oh.us', etc. In general, subdomains are domains subordinate to their parent domain. An example of very deep levels of subdomain ordering are the IPv6 reverse resolution DNS zones , e.g., 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa, which is the reverse DNS resolution domain name for

2340-405: Is 256 bytes. For 64 KB clusters, the average unused space is 32 KB. Generally, the allocation unit size is set when the storage is configured. Choosing a relatively small size compared to the files stored, results in excessive access overhead. Choosing a relatively large size results in excessive unused space. Choosing an allocation size based on the average size of files expected to be in

2418-521: Is also significant disquiet regarding the United States Government's political influence over ICANN. This was a significant issue in the attempt to create a .xxx top-level domain and sparked greater interest in alternative DNS roots that would be beyond the control of any single country. Additionally, there are numerous accusations of domain name front running , whereby registrars, when given whois queries, automatically register

Access-control list - Misplaced Pages Continue

2496-534: Is invisible to the end user and the system still works correctly. However this can degrade performance on some storage hardware that work better with contiguous blocks such as hard disk drives . Other hardware such as solid-state drives are not affected by fragmentation. A file system often supports access control of data that it manages. The intent of access control is often to prevent certain users from reading or modifying certain files. Access control can also restrict access by program in order to ensure that data

2574-569: Is maintained and serviced technically by an administrative organization operating a registry. A registry is responsible for maintaining the database of names registered within the TLD it administers. The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD and publishes the information using a special service, the WHOIS protocol. Registries and registrars usually charge an annual fee for

2652-510: Is modified in a controlled way. Examples include passwords stored in the metadata of the file or elsewhere and file permissions in the form of permission bits, access control lists , or capabilities . The need for file system utilities to be able to access the data at the media level to reorganize the structures and provide efficient backup usually means that these are only effective for polite users but are not effective against intruders. Methods for encrypting file data are sometimes included in

2730-459: Is nameless. The first-level set of domain names are the top-level domains (TLDs), including the generic top-level domains (gTLDs), such as the prominent domains com , info , net , edu , and org , and the country code top-level domains (ccTLDs). Below these top-level domains in the DNS hierarchy are the second-level and third-level domain names that are typically open for reservation by end-users who wish to connect local area networks to

2808-687: Is seeking to compromise security of the system which the access-control list is protecting. Both individual servers and routers can have network ACLs. Access-control lists can generally be configured to control both inbound and outbound traffic, and in this context they are similar to firewalls . Like firewalls, ACLs could be subject to security regulations and standards such as PCI DSS . ACL algorithms have been ported to SQL and to relational database systems . Many "modern" (2000s and 2010s) SQL -based systems, like enterprise resource planning and content management systems, have used ACL models in their administration modules. The main alternative to

2886-550: Is stored inside the allocation group itself. Additional attributes can be associated on file systems, such as NTFS , XFS , ext2 , ext3 , some versions of UFS , and HFS+ , using extended file attributes . Some file systems provide for user defined attributes such as the author of the document, the character encoding of a document or the size of an image. Some file systems allow for different data collections to be associated with one file name. These separate collections may be referred to as streams or forks . Apple has long used

2964-496: Is to provide easily recognizable and memorizable names to numerically addressed Internet resources. This abstraction allows any resource to be moved to a different physical location in the address topology of the network, globally or locally in an intranet . Such a move usually requires changing the IP address of a resource and the corresponding translation of this IP address to and from its domain name. Domain names are used to establish

3042-569: The ARPA domain serves technical purposes in the infrastructure of the Domain Name System. During the 32nd International Public ICANN Meeting in Paris in 2008, ICANN started a new process of TLD naming policy to take a "significant step forward on the introduction of new generic top-level domains." This program envisions the availability of many new or already proposed domains, as well as a new application and implementation process. Observers believed that

3120-527: The HTTP request header field Host: , or Server Name Indication . Critics often claim abuse of administrative power over domain names. Particularly noteworthy was the VeriSign Site Finder system which redirected all unregistered .com and .net domains to a VeriSign webpage. For example, at a public meeting with VeriSign to air technical concerns about Site Finder , numerous people, active in

3198-496: The IETF and other technical bodies, explained how they were surprised by VeriSign's changing the fundamental behavior of a major component of Internet infrastructure, not having obtained the customary consensus. Site Finder, at first, assumed every Internet query was for a website, and it monetized queries for incorrect domain names, taking the user to VeriSign's search site. Other applications, such as many implementations of email, treat

Access-control list - Misplaced Pages Continue

3276-680: The NTFS file system in the Windows NT family of operating systems, and the ODS-2 (On-Disk Structure-2) and higher levels of the Files-11 file system in OpenVMS . In addition to data, the file content, a file system also manages associated metadata which may include but is not limited to: A file system stores associated metadata separate from the content of the file. Most file systems store

3354-436: The com , net , org , info domains and others, use a registry-registrar model consisting of hundreds of domain name registrars (see lists at ICANN or VeriSign). In this method of management, the registry only manages the domain name database and the relationship with the registrars. The registrants (users of a domain name) are customers of the registrar, in some cases through additional layers of resellers. There are also

3432-571: The ACL model is the role-based access-control (RBAC) model. A "minimal RBAC model", RBACm , can be compared with an ACL mechanism, ACLg , where only groups are permitted as entries in the ACL. Barkley (1997) showed that RBACm and ACLg are equivalent. In modern SQL implementations, ACLs also manage groups and inheritance in a hierarchy of groups. So "modern ACLs" can express all that RBAC express and are notably powerful (compared to "old ACLs") in their ability to express access-control policy in terms of

3510-504: The ACL on an object. One of the first operating systems to provide filesystem ACLs was Multics . PRIMOS featured ACLs at least as early as 1984. In the 1990s the ACL and RBAC models were extensively tested and used to administer file permissions. POSIX 1003.1e/1003.2c working group made an effort to standardize ACLs, resulting in what is now known as "POSIX.1e ACL" or simply "POSIX ACL". The POSIX.1e/POSIX.2c drafts were withdrawn in 1997 due to participants losing interest for funding

3588-453: The IP address of a loopback interface, or the localhost name. Second-level (or lower-level, depending on the established parent hierarchy) domain names are often created based on the name of a company (e.g., bbc .co.uk), product or service (e.g. hotmail .com). Below these levels, the next domain name component has been used to designate a particular host server. Therefore, ftp.example.com might be an FTP server, www.example.com would be

3666-428: The Internet, create other publicly accessible Internet resources or run websites, such as "wikipedia.org". The registration of a second- or third-level domain name is usually administered by a domain name registrar who sell its services to the public. A fully qualified domain name (FQDN) is a domain name that is completely specified with all labels in the hierarchy of the DNS, having no parts omitted. Traditionally

3744-477: The Microsoft Windows NT , OpenVMS , and Unix-like operating systems such as Linux , macOS , and Solaris . Each accessible object contains an identifier to its ACL. The privileges or permissions determine specific access rights, such as whether a user can read from, write to, or execute an object. In some implementations, an ACE can control whether or not a user, or group of users, may alter

3822-530: The NFSv4 standard. There are two experimental implementations of NFSv4 ACLs for Linux: NFSv4 ACLs support for Ext3 filesystem and the more recent Richacls , which brings NFSv4 ACLs support for Ext4 filesystem. As with POSIX ACLs, NFSv4 ACLs are usually stored as extended attributes on Unix-like systems. NFSv4 ACLs are organized nearly identically to the Windows ;NT ACLs used in NTFS . NFSv4.1 ACLs are

3900-426: The NTFS filesystem. Windows 2000 then extended the syntax for access-control entries such that they could not only grant or deny access to entire LDAP objects, but also to individual attributes within these objects. On some types of proprietary computer hardware (in particular, routers and switches ), an access-control list provides rules that are applied to port numbers or IP addresses that are available on

3978-480: The ccTLDs combined. As of December 31, 2023, 359.8 million domain names had been registered. The right to use a domain name is delegated by domain name registrars , which are accredited by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization charged with overseeing the name and number systems of the Internet. In addition to ICANN, each top-level domain (TLD)

SECTION 50

#1732793551861

4056-589: The complete list of TLD registries and domain name registrars. Registrant information associated with domain names is maintained in an online database accessible with the WHOIS protocol. For most of the 250 country code top-level domains (ccTLDs), the domain registries maintain the WHOIS (Registrant, name servers, expiration dates, etc.) information. Some domain name registries, often called network information centers (NIC), also function as registrars to end-users. The major generic top-level domain registries, such as for

4134-421: The computer main memory can be set up as a RAM disk that serves as a storage device for a file system. File systems such as tmpfs can store files in virtual memory . A virtual file system provides access to files that are either computed on request, called virtual files (see procfs and sysfs ), or are mapping into another, backing storage. From c.  1900 and before the advent of computers

4212-519: The concepts. The logical file system layer provides relatively high-level access via an application programming interface (API) for file operations including open, close, read and write – delegating operations to lower layers. This layer manages open file table entries and per-process file descriptors. It provides file access, directory operations, security and protection. The virtual file system , an optional layer, supports multiple concurrent instances of physical file systems, each of which called

4290-609: The early network, each computer on the network retrieved the hosts file ( host.txt ) from a computer at SRI (now SRI International ), which mapped computer hostnames to numerical addresses. The rapid growth of the network made it impossible to maintain a centrally organized hostname registry and in 1983 the Domain Name System was introduced on the ARPANET and published by the Internet Engineering Task Force as RFC 882 and RFC 883. The following table shows

4368-539: The extended attributes of a file on these systems. NFSv4 ACLs are much more powerful than POSIX draft ACLs. Unlike draft POSIX ACLs, NFSv4 ACLs are defined by an actually published standard, as part of the Network File System . NFSv4 ACLs are supported by many Unix and Unix-like operating systems. Examples include AIX , FreeBSD , Mac OS X beginning with version 10.4 (" Tiger "), or Solaris with ZFS filesystem, support NFSv4 ACLs, which are part of

4446-416: The file system. This is very effective since there is no need for file system utilities to know the encryption seed to effectively manage the data. The risks of relying on encryption include the fact that an attacker can copy the data and use brute force to decrypt the data. Additionally, losing the seed means losing the data. Some operating systems allow a system administrator to enable disk quotas to limit

4524-404: The first five .com domains with the dates of their registration: and the first five .edu domains: Today, the Internet Corporation for Assigned Names and Numbers (ICANN) manages the top-level development and architecture of the Internet domain name space. It authorizes domain name registrars , through which domain names may be registered and reassigned. The domain name space consists of

4602-414: The first quarter of 2015, 294 million domain names had been registered. A large fraction of them are in the com TLD, which as of December 21, 2014, had 115.6 million domain names, including 11.9 million online business and e-commerce sites, 4.3 million entertainment sites, 3.1 million finance related sites, and 1.8 million sports sites. As of July 15, 2012, the com TLD had more registrations than all of

4680-476: The highest level of domain names of the Internet. Top-level domains form the DNS root zone of the hierarchical Domain Name System . Every domain name ends with a top-level domain label. During the growth of the Internet, it became desirable to create additional generic top-level domains. As of October 2009, 21 generic top-level domains and 250 two-letter country-code top-level domains existed. In addition,

4758-406: The interest of the Internet infrastructure component for which VeriSign was the steward. Despite widespread criticism, VeriSign only reluctantly removed it after the Internet Corporation for Assigned Names and Numbers (ICANN) threatened to revoke its contract to administer the root name servers. ICANN published the extensive set of letters exchanged, committee reports, and ICANN decisions. There

SECTION 60

#1732793551861

4836-445: The left of .com, .net, and the other top-level domains. As an example, in the domain example.co.uk , co is the second-level domain. Next are third-level domains, which are written immediately to the left of a second-level domain. There can be fourth- and fifth-level domains, and so on, with virtually no limitation. Each label is separated by a full stop (dot). An example of an operational domain name with four levels of domain labels

4914-500: The length of a file name. Some file systems match file names as case sensitive and others as case insensitive. For example, the names MYFILE and myfile match the same file for case insensitive, but different files for case sensitive. Most modern file systems allow a file name to contain a wide range of characters from the Unicode character set. Some restrict characters such as those used to indicate special attributes such as

4992-595: The names of all the files in one directory in one place—the directory table for that directory—which is often stored like any other file. Many file systems put only some of the metadata for a file in the directory table, and the rest of the metadata for that file in a completely separate structure, such as the inode . Most file systems also store metadata not associated with any one particular file. Such metadata includes information about unused regions— free space bitmap , block availability map —and information about bad sectors . Often such information about an allocation group

5070-410: The new name space created, registrars use several key pieces of information connected with a domain: A domain name consists of one or more labels, each of which is formed from the set of ASCII letters, digits, and hyphens (a–z, A–Z, 0–9, -), but not starting or ending with a hyphen. The labels are case-insensitive; for example, 'label' is equivalent to 'Label' or 'LABEL'. In the textual representation of

5148-442: The new rules could result in hundreds of new top-level domains to be registered. In 2012, the program commenced, and received 1930 applications. By 2016, the milestone of 1000 live gTLD was reached. The Internet Assigned Numbers Authority (IANA) maintains an annotated list of top-level domains in the DNS root zone database. For special purposes, such as network testing, documentation, and other applications, IANA also reserves

5226-484: The owner of example.org could provide subdomains such as foo.example.org and foo.bar.example.org to interested parties. Many desirable domain names are already assigned and users must search for other acceptable names, using Web-based search features, or WHOIS and dig operating system tools. Many registrars have implemented domain name suggestion tools which search domain name databases and suggest available alternative domain names related to keywords provided by

5304-532: The project and turning to more powerful alternatives such as NFSv4 ACL. As of December 2019, no live sources of the draft could be found on the Internet, but it can still be found in the Internet Archive . Most of the Unix and Unix-like operating systems (e.g. Linux since 2.5.46 or November 2002, FreeBSD , or Solaris ) support POSIX.1e ACLs (not necessarily draft 17). ACLs are usually stored in

5382-765: The same computer . A distributed file system is a protocol that provides file access between networked computers. A file system provides a data storage service that allows applications to share mass storage . Without a file system, applications could access the storage in incompatible ways that lead to resource contention , data corruption and data loss . There are many file system designs and implementations – with various structure and features and various resulting characteristics such as speed, flexibility, security, size and more. Files systems have been developed for many types of storage devices , including hard disk drives (HDDs), solid-state drives (SSDs), magnetic tapes and optical discs . A portion of

5460-446: The service of delegating a domain name to a user and providing a default set of name servers. Often, this transaction is termed a sale or lease of the domain name, and the registrant may sometimes be called an "owner", but no such legal relationship is actually associated with the transaction, only the exclusive right to use the domain name. More correctly, authorized users are known as "registrants" or as "domain holders". ICANN publishes

5538-420: The services offered, a feature that is used to manage the traffic of large, popular websites. Web hosting services , on the other hand, run servers that are typically assigned only one or a few addresses while serving websites for many domains, a technique referred to as virtual web hosting . Such IP address overloading requires that each request identifies the domain name being referenced, for instance by using

5616-429: The storage tends to minimize unusable space. As a file system creates, modifies and deletes files, the underlying storage representation may become fragmented . Files and the unused space between files will occupy allocation blocks that are not contiguous. A file becomes fragmented if space needed to store its content cannot be allocated in contiguous blocks. Free space becomes fragmented when files are deleted. This

5694-442: The terms file system , filing system and system for filing were used to describe methods of organizing, storing and retrieving paper documents. By 1961, the term file system was being applied to computerized filing alongside the original meaning. By 1964, it was in general use. A local file system's architecture can be described as layers of abstraction even though a particular file system design may not actually separate

5772-539: The user. The business of resale of registered domain names is known as the domain aftermarket . Various factors influence the perceived value or market value of a domain name. Most of the high-prize domain sales are carried out privately. Also, it is called confidential domain acquiring or anonymous domain acquiring. Intercapping is often used to emphasize the meaning of a domain name, because DNS names are not case-sensitive. Some names may be misinterpreted in certain uses of capitalization. For example: Who Represents ,

5850-479: The valid DNS character set by an encoding called Punycode . For example, københavn.eu is mapped to xn--kbenhavn-54a.eu. Many registries have adopted IDNA. The first commercial Internet domain name, in the TLD com , was registered on 15 March 1985 in the name symbolics.com by Symbolics Inc., a computer systems firm in Cambridge, Massachusetts. By 1992, fewer than 15,000 com domains had been registered. In

5928-400: The way in which administrators view organizations. For data interchange, and for "high-level comparisons", ACL data can be translated to XACML . Filesystem In computing , a file system or filesystem (often abbreviated to FS or fs ) governs file organization and access. A local file system is a capability of an operating system that services the applications running on

6006-582: The websites of many organizations on just a few servers. The hierarchical DNS labels or components of domain names are separated in a fully qualified name by the full stop (dot, . ). The character set allowed in the Domain Name System is based on ASCII and does not allow the representation of names and words of many languages in their native scripts or alphabets. ICANN approved the Internationalized domain name (IDNA) system, which maps Unicode strings used in application user interfaces into

6084-465: Was divided into two main groups of domains. The country code top-level domains (ccTLD) were primarily based on the two-character territory codes of ISO-3166 country abbreviations. In addition, a group of seven generic top-level domains (gTLD) was implemented which represented a set of categories of names and multi-organizations. These were the domains gov , edu , com , mil , org , net , and int . These two types of top-level domains (TLDs) are

#860139