Computer Science
Domain Name System
The Domain Name System (DNS) is a decentralized system that translates domain names into IP addresses, allowing users to access websites and other resources using human-readable names. It functions like a phone book for the internet, enabling users to locate and connect to specific web servers and services. DNS plays a crucial role in facilitating communication and data exchange across the internet.
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11 Key excerpts on "Domain Name System"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 6 Domain Name System The Domain Name System ( DNS ) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name www.example.com translates to the addresses 192.0.32.10 (IPv4) and 2620:0:2d0:200::10 (IPv6). The Domain Name System makes it possible to assign domain names to groups of Internet resources and users in a meaningful way, independent of each entity's physical location. Because of this, World Wide Web (WWW) hyperlinks and Internet contact information can remain consistent and constant even if the current Internet routing arrangements change or the participant uses a mobile device. Internet domain names are easier to remember than IP addresses such as 208.77.188.166 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6). Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates them. The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 5 Domain Name System and Domain Name System Security Extensions Domain Name System The Domain Name System ( DNS ) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. The Domain Name System makes it possible to assign domain names to groups of Internet resources and users in a meaningful way, independent of each entity's physical location. Because of this, World Wide Web (WWW) hyperlinks and Internet contact information can remain consistent and constant even if the current Internet routing arrangements change or the participant uses a mobile device. Internet domain names are easier to remember than IP addresses such as 208.77.188.166 (IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6). Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates them. The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains.
eBook - ePub- Matthew Hickey, Jennifer Arcuri(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
Chapter 5 The Domain Name SystemComputers that are part of a network (such as the Internet) have a numerical address that must be used if you want to connect one machine to another. Remembering a 32-bit number—even when converted to decimal and neatly formatted in the form 58.199.11.2—for every computer to which you want to connect isn't practical. We can't usually remember the phone numbers of just a handful of our contacts, instead storing them in some form of address book. Most of us would agree that it is essential to have some form of lookup table or, at the least, a list of names and numbers—whether dialing a phone or a computer—especially if those entries are frequently updated.Enter the Domain Name System (DNS). In this chapter, you will first learn about DNS—about name servers and the software that runs on them. Then you will learn how to interrogate a name server, find vulnerabilities in the software running on these servers, and, ultimately, exploit them.The Implications of Hacking DNS
Companies rely on name servers to provide answers to queries—queries like, “What is the IP address of www.yourcompany.com ?” Taking down or limiting the capabilities of a company's name server can prevent customers and employees from accessing a range of services (not just websites), thus impacting a company's credibility, reputation, and revenue. Furthermore, the way in which DNS has been designed and implemented can be exploited to perform distributed denial-of-service (DDOS) attacks, where the power of multiple machines can be harnessed to send large amounts of traffic to a single server, rendering it useless and unable to function correctly.Such attacks occur almost constantly somewhere in the world and are often difficult to defend against or trace. Even the root name servers
eBook - ePubExpert Linux Administration Guide
Administer and Control Linux Filesystems, Networking, Web Server, Virtualization, Databases, and Process Control (English Edition)
- Vishal Rai(Author)
- 2022(Publication Date)
- BPB Publications(Publisher)
HAPTER 13Domain Name System
Introduction
It is human nature to easily remember a name rather than a numeric string. In the Internet world, the users can access the website using a domain name or IP address, but the domain name is easy to remember. When the user types the website name in a web browser, the system converts the domain name to its corresponding public IP address and displays the home page of the website. Hence, domain name is defined as basically a string of text that maps to an IP address, used to access a website from client . The process between DNS and ISP (Internet Service Provides ) will be discussed in the topic Working of DNS .Structure
In this chapter, we will cover the following topics:- Introduction to DNS
- DNS database
- Working of DNS
- Introduction to DNS zones
- Authoritative DNS Server
- DNS caching name server
- Getting your own domain from a registrar
- Primary DNS and Secondary DNS configuration
- DNS zones file syntax
- /etc/named.conf file common syntax
- DNS resource record
- Allow/deny DNS in UTM/Linux firewall
- Client machine network setting for Oracle Virtual Box
- Testing DNS server from Green-Zone
Objective
This chapter deals with the introduction to DNS, the function of DNS, installation & configuration of DNS for an organization, how to add a host record to DNS, how to configure the DNS file, etc. Users will learn how to configure Master, Slave, Caching-only and Forwarding-only, DNS Zone (Forward and Reverse), DNS lookup, and DNS clients in detail.Introduction to DNS
DNS stands for Domain Name System. It resolves the website name to its corresponding IP address and IP address to the Domain name. In other words, the objective of DNS is to resolve the fully qualified domain name (FQDN
eBook - PDFCloud Computing Networking
Theory, Practice, and Development
- Lee Chao(Author)
- 2015(Publication Date)
- Auerbach Publications(Publisher)
In today’s Internet computing environment, each web server has a distinct name representing the host organization. By doing so, users can Figure 5.5 DHCP statistics. 168 CLOUD COMPUTING NETWORKING easily remember them during web surfing. It is necessary to resolve a web server name to the corresponding IP address, so the web server can communicate with computers installed with the web browser. Also, all e-mail servers have meaningful names so that users can easily identify e-mail senders and receivers. Again, the name service is required to resolve the names of e-mail servers and the corresponding IP addresses. In summary, the name service is a critical component for supporting the daily operation of an organization. The DNS is a name service protocol, which is widely used for name services. DNS works like a distributed database, which contains the pairs of names and IP addresses. When a client requests the IP address for a given name, DNS searches the corre-sponding IP address in the distributed database. Once the IP address is found, DNS returns the IP address to the client. Reversely, DNS can find the corresponding name for a given IP address. Later, in the hands-on practice, you will learn how to install and configure a DNS service and how to manage the DNS server. 5.3.1 Naming Hierarchy The naming of a network host uses the naming convention of Active Directory. For example, myhost.mydepartment.mycollege.myuniversity.edu. The host name is a sequence of names separated with periods. This name rep-resents the hierarchical structure of a university. The name on the right has more general use than the one on the left. The right most name is the most general name that is provided by the top-level domain. There are only a limited number of such domains that are managed by the Internet Corporation for Assigned Names and Numbers (ICANN). The commonly used top-level domains are listed in Table 5.1.
eBook - PDF- Gilbert Held(Author)
- 2002(Publication Date)
- Auerbach Publications(Publisher)
Recognizing this potential problem, this author uses the term “DNS” to reference the system of servers. 126 The ABCs of TCP/IP The DNS represents both a distributed database used by TCP/IP applications to map between host names and IP addresses as well as a protocol conveyed via UDP to distribute information between clients and servers. As discussed in another section in this chapter (The Domain Name Structure), the DNS employs a hierarchical naming scheme similar to a file system tree which facilitates the mapping of host names to IP addresses and, if required, an opposite mapping from IP addresses to host names. Purpose The purpose of the DNS is to provide the TCP/IP community with a mechanism to translate host addresses into IP addresses because all routing is based on an examination of IP addresses. To accomplish this translation process, a series of Domain Name Servers are used to create a distributed database that contains the names and addresses of all reachable hosts on a TCP/IP network. That network can be a corporate intranet, the portion of the Internet operated by an Internet service provider (ISP), or the entire Internet. The Domain Name Structure Internet host names employ a hierarchical address structure. This address structure consists of a top-level domain, a sub-domain, and a host name. Initially, top-level domain names such as .com, .gov, and .edu, as well as IP addresses, were assigned and maintained by the Internet Assigned Numbers Authority (IANA), which was responsible for the overall coordination and management of the DNS. Controversy about the IANA having sole control of top-level domains occurred during the past few years, with the result that the Internet Corporation for Assigned Names and Numbers (ICANN) was formed as a nonprofit organization to take over responsibility for the allocation of IP address space as well as for DNS and root server management.
eBook - PDFData Networks
Routing, Security, and Performance Optimization
- Tony Kenyon(Author)
- 2002(Publication Date)
- Digital Press(Publisher)
There is plenty of scope for denial-of-service attacks or host intrusion. Load—As the network grows, the service demands placed on the cen-tral host system can become intolerable. The load placed on the net-work also becomes a major problem. To overcome these problems a hierarchical distributed database is required, together with dynamic name synchronization and name query mechanisms. In November 1983 such a system was proposed in RFC 882 and RFC 883 (now both obsolete); this system is called the Domain Name Service (DNS). 2.3.2 Domain Name System (DNS) The Domain Name System (DNS) comprises a client/server protocol together with a distributed database that holds name-to-IP-address map-pings. The DNS is accessed by IP applications to dynamically discover address-name bindings and e-mail routing information. To promote scal-ability and better performance, the administration of parts of the database is devolved locally. Each site (e.g., campus, company, or department) typically maintains its own database for the local domain and runs a server program that other DNS servers can query over an IP network. The DNS is a large topic, and a complete discussion is outside the scope of this book. Here we will briefly review its operation and discuss the pertinent issues for network design and performance analysis. For more detailed information, the inter- 108 2.3 Name-to-address mapping ested reader is referred to [28, 31–34]. DNS extensions to support IPv6 are specified in [35]. Before we discuss DNS operations we first need to understand the struc-ture and implementation of domain names. Domain names The DNS structure contains a hierarchy of names, not unlike the UNIX file system in organization. The highest level, or root, of the DNS is unnamed (null). Each node in the tree represents a domain, which is a segment of the overall name database.
eBook - ePub- J.K. Petersen(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
.au [Australia], etc.). This naming scheme is not completely consistent, but it is helpful in most circumstances. It also is not a guarantee of location, as a system may remotely dial into a domain in another country. See domain name, for further details on Internet naming, and domain name server, Domain Name System, firewall, host, Internet, server.domain name A unique identifier, usually expressed in alphanumeric characters, to a computer domain. Local networks that are not connected to outside entities can setup this domain name in any way they choose or according to the domain naming parameters of the network software that is running on the system. On the Internet, however, which is a global distributed network, it is necessary to maintain an extensive database of domains in order that each one is uniquely identified. Thus, a domain name on the Internet must be registered with one of the assigned registration entities, the oldest of which is InterNIC. See domain name, Internet.domain name, Internet A globally unique identifier for a domain that is continually or occasionally online on the Internet through an Internet Access Provider (IAP), which may provide additional services as an Internet Services Provider (ISP). This identifier is used by the system to locate a domain in order to send and receive files, email, messages, routing information, and other network traffic. A certain flexibility is inherent in this scheme in that levels below the IAP can be rearranged according to the needs of the local network.The domain name is actually a name resolved to an Internet Protocol (IP) address, which is composed of numbers, but the name is what is familiar to most users, and it is automatically converted by the system. Once an Internet domain name has been assigned, such as ourdomain.org
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 9 Domain Name A domain name is an identification label that defines a realm of administrative autonomy, authority, or control in the Internet. Domain names are also hostnames that identify Internet Protocol (IP) resources such as web sites. Domain names are formed by the rules and procedures of the Domain Name System (DNS). Domain names are used in various networking contexts and application-specific naming and addressing purposes. They are organized in subordinate levels (subdomains) of the DNS root domain, which 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 , net 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 that wish to connect local area networks to the Internet, run web sites, or create other publicly accessible Internet resources. The registration of these domain names is usually administered by domain name registrars who sell their services to the public. Individual Internet host computers use domain names as host identifiers, or hostnames. Hostnames are the leaf labels in the Domain Name System usually without further subordinate domain name space. Hostnames appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites. 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 DomainKeys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs). An important purpose of domain names is to provide easily recognizable and memorizable names to numerically addressed Internet resources.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 5 Domain Name A domain name is an identification label that defines a realm of administrative auto-nomy, authority, or control in the Internet. Domain names are also hostnames that identify Internet Protocol (IP) resources such as web sites. Domain names are formed by the rules and procedures of the Domain Name System (DNS). Domain names are used in various networking contexts and application-specific naming and addressing purposes. They are organized in subordinate levels (subdomains) of the DNS root domain, which 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 , net 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 that wish to connect local area networks to the Internet, run web sites, or create other publicly accessible Internet resources. The registration of these domain names is usually administered by domain name registrars who sell their services to the public. Individual Internet host computers use domain names as host identifiers, or hostnames. Hostnames are the leaf labels in the Domain Name System usually without further subordinate domain name space. Hostnames appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites. 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 DomainKeys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs). An important purpose of domain names is to provide easily recognizable and memo-rizable names to numerically addressed Internet resources.
eBook - PDF- Henry M. Walker(Author)
- 2012(Publication Date)
- Chapman and Hall/CRC(Publisher)
In con-sidering these tables, the Internet is now so large that it is not practical for any one machine to record all possible addresses. Instead, central machines are designated as authorities for various parts of the network, and a local machine may or may not record the few domain names, IP numbers, and Ethernet addresses it actually uses. Any machine attempting to contact another machine must first contact an authoritative server in charge of keeping track of the necessary IP addresses so that it has access to that information. To see how this type of lookup is done, suppose the local machine (steenrod.cs.grinnell. edu) needs to determine the IP number for cs.utexas.edu. When the machine (steenrod) is first turned on, it has no information concerning other IP numbers, but its initial configu-ration includes information that a local domain name server (DNS) can be reached at grinnell.edu—IP number 132.161.10.11. If this server is unavailable, it has the IP number for a secondary network information server (NIS) . The DNS and NIS machines maintain databases with domain names and IP numbers in a binary format that facilitates quick lookup. In fact, for efficiency, this information is often stored in two tables—one based on domain name and the other on IP number—so that searches by either domain name or IP number can be performed particularly fast. In searching for the IP number for cs.utexas.edu, the local machine first asks its local DNS, which has authority over the local machine’s network, but which may or may not know about the rest of the world. In handling this request for information, this local DNS consults its tables to attempt to locate the needed IP number. If this information is not in the table, the local DNS initiates one or more requests to track down the desired IP num-ber for cs.utexas.edu. Thus, the local DNS may consult a secondary NIS source, which is the authority for a wider area of the network.
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