2 years, 5 months ago
How does DNS work?
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DNS organizes hostnames in a domain hierarchy. A domain is a collection of sites that are related in some sense—because they form a proper network (e.g., all machines on a campus, or all hosts on BITNET), because they all belong to a certain organization (e.g., the U.S. government), or because they're simply geographically close. For instance, universities are commonly grouped in the edu domain, with each university or college using a separate subdomain, below which their hosts are subsumed. Groucho Marx University have the groucho.edu domain, while the LAN of the Mathematics department is assigned maths.groucho.edu. Hosts on the departmental network would have this domain name tacked onto their hostname, so erdos would be known as erdos maths.groucho.edu. This is called the fully qualified domain name (FQDN), which uniquely identifies this host worldwide.
A part of the domain namespace
Depending on its location in the name hierarchy, a domain may be called top-level, second-level, or third-level. More levels of subdivision occur, but they are rare. This list details several top-level domains you may see frequently:
Domain Description
edu
(Mostly U.S.) educational institutions like universities.
com
Commercial organizations and companies.
org
Non-commercial organizations. Private UUCP networks are often in this domain.
net
Gateways and other administrative hosts on a network.
mil
U.S. military institutions.
gov
U.S. government institutions.
uucp
Officially, all site names formerly used as UUCP names without domains have been moved to this domain.
Historically, the first four of these were assigned to the U.S., but recent changes in policy have meant that these domains, named global Top Level Domains (gTLD), are now considered global in nature. Negotiations are currently underway to broaden the range of gTLDs, which may result in increased choice in the future.
Outside the U.S., each country generally uses a top-level domain of its own named after the two-letter country code defined in ISO-3166. Finland, for instance, uses the fi domain; fr is used by France, de by Germany, and au by Australia. Below this top-level domain, each country's NIC is free to organize hostnames in whatever way they want. Australia has second-level domains similar to the international top-level domains, named com.au and edu.au. Other countries, like Germany, don't use this extra level, but have slightly long names that refer directly to the organizations running a particular domain. It's not uncommon to see hostnames like ftp.informatik.uni-erlangen.de. Chalk that up to German efficiency.
Of course, these national domains do not imply that a host below that domain is actually located in that country; it means only that the host has been registered with that country's NIC. A Swedish manufacturer might have a branch in Australia and still have all its hosts registered with the se top-level domain.
Organizing the namespace in a hierarchy of domain names nicely solves the problem of name uniqueness; with DNS, a hostname has to be unique only within its domain to give it a name different from all other hosts worldwide. Furthermore, fully qualified names are easy to remember. Taken by themselves, these are already very good reasons to split up a large domain into several subdomains.
DNS does even more for you than this. It also allows you to delegate authority over a subdomain to its administrators. For example, the maintainers at the Groucho Computing Center might create a subdomain for each department; we already encountered the math and physics subdomains above. When they find the network at the Physics department too large and chaotic to manage from outside (after all, physicists are known to be an unruly bunch of people), they may simply pass control of the physics.groucho.edu domain to the administrators of this network. These administrators are free to use whatever hostnames they like and assign them IP addresses from their network in whatever fashion they desire, without outside interference.
A part of the domain namespace
Depending on its location in the name hierarchy, a domain may be called top-level, second-level, or third-level. More levels of subdivision occur, but they are rare. This list details several top-level domains you may see frequently:
Domain Description
edu
(Mostly U.S.) educational institutions like universities.
com
Commercial organizations and companies.
org
Non-commercial organizations. Private UUCP networks are often in this domain.
net
Gateways and other administrative hosts on a network.
mil
U.S. military institutions.
gov
U.S. government institutions.
uucp
Officially, all site names formerly used as UUCP names without domains have been moved to this domain.
Historically, the first four of these were assigned to the U.S., but recent changes in policy have meant that these domains, named global Top Level Domains (gTLD), are now considered global in nature. Negotiations are currently underway to broaden the range of gTLDs, which may result in increased choice in the future.
Outside the U.S., each country generally uses a top-level domain of its own named after the two-letter country code defined in ISO-3166. Finland, for instance, uses the fi domain; fr is used by France, de by Germany, and au by Australia. Below this top-level domain, each country's NIC is free to organize hostnames in whatever way they want. Australia has second-level domains similar to the international top-level domains, named com.au and edu.au. Other countries, like Germany, don't use this extra level, but have slightly long names that refer directly to the organizations running a particular domain. It's not uncommon to see hostnames like ftp.informatik.uni-erlangen.de. Chalk that up to German efficiency.
Of course, these national domains do not imply that a host below that domain is actually located in that country; it means only that the host has been registered with that country's NIC. A Swedish manufacturer might have a branch in Australia and still have all its hosts registered with the se top-level domain.
Organizing the namespace in a hierarchy of domain names nicely solves the problem of name uniqueness; with DNS, a hostname has to be unique only within its domain to give it a name different from all other hosts worldwide. Furthermore, fully qualified names are easy to remember. Taken by themselves, these are already very good reasons to split up a large domain into several subdomains.
DNS does even more for you than this. It also allows you to delegate authority over a subdomain to its administrators. For example, the maintainers at the Groucho Computing Center might create a subdomain for each department; we already encountered the math and physics subdomains above. When they find the network at the Physics department too large and chaotic to manage from outside (after all, physicists are known to be an unruly bunch of people), they may simply pass control of the physics.groucho.edu domain to the administrators of this network. These administrators are free to use whatever hostnames they like and assign them IP addresses from their network in whatever fashion they desire, without outside interference.
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DNS, stands for " Domain Name System" and helps resolving names to IP numbers as it is much easier for people to remember logical names rather then a 12 digit number.
DNS uses 3 major components ?Resolvers (client)?, Name Servers? and ?Domain Name Space?. In basic DNS communication a client (Resolver) sends a query to a Name Server, which returns with the requested information, or an address for another Name Server, an error message is received if the query gives no results
Installing and configuring DNS
Installing DNS on Windows NT is very easy, but configuring it can be hard. The first thing you must do is to install the DNS service. Before you install the service remember that your server must have a static IP number.
Login as administrator, in the control panel double click on network, click on services and add, now choose Microsoft DNS Server and click OK. click OK. Under the Protocol tab, mark the TCP/IP Protocol, then click Properties, under DNS, where it says Domain, type your company name.com and click OK. Reboot the server.
Reinstall service pack 6a
Configuring DNS Server
Login as Administrator, in the control panel double click on network, click on Protocols and choose TCP/IP Properties, click on DNS, and in DNS Service Search Order click Add. type in the IP address which you earlier assigned to the server. (the one you are on now).
1. click on "Start > Programs > Administrative Tools > DNS Manager".
2. click on the DNS menu, and then choose "New Server".
3. Type the IP address of your DNS Server (192.168.1.77), and click OK.
If you need DNS Query means you can get the DNS Query here http://www.whoisxy.com/
DNS uses 3 major components ?Resolvers (client)?, Name Servers? and ?Domain Name Space?. In basic DNS communication a client (Resolver) sends a query to a Name Server, which returns with the requested information, or an address for another Name Server, an error message is received if the query gives no results
Installing and configuring DNS
Installing DNS on Windows NT is very easy, but configuring it can be hard. The first thing you must do is to install the DNS service. Before you install the service remember that your server must have a static IP number.
Login as administrator, in the control panel double click on network, click on services and add, now choose Microsoft DNS Server and click OK. click OK. Under the Protocol tab, mark the TCP/IP Protocol, then click Properties, under DNS, where it says Domain, type your company name.com and click OK. Reboot the server.
Reinstall service pack 6a
Configuring DNS Server
Login as Administrator, in the control panel double click on network, click on Protocols and choose TCP/IP Properties, click on DNS, and in DNS Service Search Order click Add. type in the IP address which you earlier assigned to the server. (the one you are on now).
1. click on "Start > Programs > Administrative Tools > DNS Manager".
2. click on the DNS menu, and then choose "New Server".
3. Type the IP address of your DNS Server (192.168.1.77), and click OK.
If you need DNS Query means you can get the DNS Query here http://www.whoisxy.com/
You can leave an optional "tip" with Mahalo's virtual currency, Mahalo Dollars. If you are asking a difficult question that might require some research, or if you'd like a wide variety of feedback, a higher tip often leads to more answers to your question.
M$
The Domain Name System(DMS) is basically a database of host information.
Here are some interesting facts related to DNS working based on my web search .
---quote---
http://www.redfusionmedia.com/images/dns_chart.gif
To determine which primary name server contains your Domain Name Records, your computer contacts the root level internic name server maintained by InterNIC.
Next, the root level internic name server returns the IP address of the primary name server responsible for requesting the domain.
The primary name server is the next machine to be contacted by the your computer.
The primary name server contains the IP address for the domain name, fulfilling the your computer’s request.
Finally the hosting server can return to the web browser with the IP address.
Using the IP address, the web browser is then able to contact the company’s web server and retrieve your web pages.
---end quote----
Here are some interesting facts related to DNS working based on my web search .
---quote---
To determine which primary name server contains your Domain Name Records, your computer contacts the root level internic name server maintained by InterNIC.
Next, the root level internic name server returns the IP address of the primary name server responsible for requesting the domain.
The primary name server is the next machine to be contacted by the your computer.
The primary name server contains the IP address for the domain name, fulfilling the your computer’s request.
Finally the hosting server can return to the web browser with the IP address.
Using the IP address, the web browser is then able to contact the company’s web server and retrieve your web pages.
---end quote----
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M$
GRC / Steve Gibson explains it in his podcast, specifically on #155 http://media.grc.com/sn/SN-155.mp3
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