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    faizan341 is offline Senior Member+
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    Default what is DNS

    networking main dns kya hota hai or koi mujhey switch or hub main farq bata sakta hai or inki pictures bhi dikha den

    thanks

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    nom is offline Senior Member+
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    HUBS VS SWITCH

    About Hubs

    Hubs are very dumb network devices. They allow all devices that are connected to it to communicate to each other. It makes no decisions about traffic direction, it doesn't inspect traffic quality or verify packet integrity. All network data it receives on one port will be immediately transmitted out all the other ports, so each computer must take it's turn before sending data. This is called half-duplex, it is very inefficient.

    Here is a great example. I have 3 computers plugged into a 10 M-Bit hub:

    * faizan
    * imran
    * nom

    I am on the 'faizan' computer and wish to send a file to the 'nom' computer. imran will hear all the talking but will not take action into receiving the file. Each piece of network data that imran receives must be inspected by imran and after imran realizes that it is not for him the data is ignored.

    So the total bandwidth is shared among the computers. Whatever bandwidth faizan and nom are not using for this file transfer is left for imran to use. My grandpa would be more familiar with this analogy; using a hub on the network can be compared to those old party lines people had when you shared a phone line with several neighbors.

    Clue: Hubs distribute all of the data they receive to all the network devices they are connected to. This is a highly in-efficient use of your network bandwidth. However, there is no processing delay created by the hub because the hub, by definition, does no processing.




    About Switches


    A switch can be considered a 'smart' hub. It will actively look at the traffic it receives and based on the destination address it will direct that traffic only to the port needed. The switch listens to each port at the same time without any interference. A computer plugged directly into the switch will not receive unnecessary traffic and can transmit to the switch whenever it needs to, this leaves all the bandwidth available to each machine.

    The switch memorizes the MAC address of each host and which port it resides on. This is how it can intelligently direct traffic.

    Switches can be many times more expensive than hubs, the costs keeps increasing as you look for more features. Features include bandwidth monitoring, Spanning Tree Protocol, being stackable (the ability to have a faster data transfer from one switch to another than the port speed), etc.
    Network Implementation

    If you already have purchased several hubs and are experiencing a slow network, a single switch can solve your problem. Instead of having all your hubs daisy chained together, you can separate them by using the switch as the center point between all the hubs. Any traffic destined from a computer on hub one to a computer on hub two will be directed by the switch and you will avoid traffic propagating to the other hubs.

    When it comes to purchasing network equipment, it is very cost effective to get twice as many ports as what you need. Network growth is something that you can count on in almost every business.
    n O m
    Why is it drug addicts and computer aficionados are both called users?

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    nom is offline Senior Member+
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    DNS


    The Domain Name System (abbreviated DNS) is an Internet directory service. DNS is how domain names are translated into IP addresses, and DNS also controls email delivery. If your computer cannot access DNS, your web browser will not be able to find web sites, and you will not be able to receive or send email.

    The DNS system consists of three components: DNS data (called resource records), servers (called name servers), and Internet protocols for fetching data from the servers.

    The billions of resource records in the DNS are split into millions of files called zones. Zones are kept on authoritative servers distributed all over the Internet, which answer queries based on the resource records stored in the zones they have copies of. Caching servers ask other servers for information and cache any replies. Most name servers are authoritative for some zones and perform a caching function for all other DNS information. Large name servers are often authoritative for tens of thousands of zones, but most name servers are authoritative for just a few zones.



    or




    What is DNS?

    Domain Name System (DNS) is a database system that translates a computer's fully qualified domain name into an IP address.

    Networked computers use IP addresses to locate and connect to each other, but IP addresses can be difficult for people to remember. For example, on the web, it's much easier to remember the domain name www.amazon.com than it is to remember its corresponding IP address (207.171.166.48). DNS allows you to connect to another networked computer or remote service by using its user-friendly domain name rather than its numerical IP address. Conversely, Reverse DNS (rDNS) translates an IP address into a domain name.

    Each organization that maintains a computer network will have at least one server handling DNS queries. That server, called a name server, will hold a list of all the IP addresses within its network, plus a cache of IP addresses for recently accessed computers outside the network. Each computer on each network needs to know the location of only one name server. When your computer requests an IP address, one of three things happens, depending on whether or not the requested IP address is within your local network:

    * If the requested IP address is registered locally (i.e., it's within your organization's network), you'll receive a response directly from one of the local name servers listed in your workstation configuration. In this case, there usually is little or no wait for a response.

    * If the requested IP address is not registered locally (i.e., outside your organization's network), but someone within your organization has recently requested the same IP address, then the local name server will retrieve the IP address from its cache. Again, there should be little or no wait for a response.

    * If the requested IP address is not registered locally, and you are the first person to request information about this system in a certain period of time (ranging from 12 hours to one week), then the local name server will perform a search on behalf of your workstation. This search may involve querying two or more other name servers at potentially very remote locations. These queries can take anywhere from a second or two up to a minute (depending on how well connected you are to the remote network and how many intermediate name servers must be contacted). Sometimes, due to the lightweight protocol used for DNS, you may not receive a response. In these cases, your workstation or client software may continue to repeat the query until a response is received, or you may receive an error message.

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    nom is offline Senior Member+
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    FOR EXAMPLE

    Configure DNS in Windows XP?


    Right click on Local Area Connections



    In the Local Area Connection Properties window under the General tab, select Internet Protocol (TCP/IP) and click Properties



    In the TCP/IP window, under the General tab click Advanced.



    In the field provided enter ad.uab.edu



    Choose Add New Account, then click Next



    Lastly, close all windows

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    very well, that is cool sharing.

  6. #6
    meharunnisa is offline Senior Member+
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    Realy very informative sharing. Thanks

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