What happens when we type in a URL.

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test

Hi All,

What happens when we type a URL in the url box. FOr ex, when we type say
www.hotmail.com, I believe the request will go to some central server,where
it knows that hotmail.com is mapped to so and so ipaddress and then the
files are obtained from that ipaddress.

The questions where is the central database/locations. Can some throw any
ideas on this.

Thanks.
 
test said:
Hi All,

What happens when we type a URL in the url box. FOr ex, when we type say
www.hotmail.com, I believe the request will go to some central server,
where it knows that hotmail.com is mapped to so and so ipaddress and then
the files are obtained from that ipaddress.

The questions where is the central database/locations. Can some throw any
ideas on this.

Thanks.
Click to expand...

It's called DNS, Domain Name System, and there is a lot of information on it
via Google. Exactly which DNS server you use at a particular moment
depends on your ISP at the moment.

HTH
-pk
 
Hi All,

What happens when we type a URL in the url box. FOr ex, when we type say
www.hotmail.com, I believe the request will go to some central server,
Click to expand...


That's correct. It's called a DNS (Domain Name System) Server.

where
it knows that hotmail.com is mapped to so and so ipaddress and then the
files are obtained from that ipaddress.
Click to expand...



Also correct. The "real" address of the web site is that IP address,
not the URL.


The questions where is the central database/locations. Can some throw any
ideas on this.
Click to expand...


Usually the DNS Server is one automatically provided by your ISP, but
you can specify a different one in the Network Connections dialog.
Seldom is it necessary to use any but the one your ISP Provides.
 
So does that mean that every ISP will have a DNS server,and where is this
running. That is the whole piont I am not understanding.

I thought there should only be one DNS server running at a central location
which maps names to ip addresses(and all the requests regarding which ISP's
they are from should go to that server). Regardless there should be only
central database which maps domain names to ip addresses. Please share your
thoughts.

Thnx.
 
So does that mean that every ISP will have a DNS server,
Click to expand...



"Every" is a very strong word that I'm always reluctant to use. I
wouldn't be surprised if some don't and share another ISP's server.
Still the answer to your question is generally yes.

and where is this
running.
Click to expand...


At the ISP's site.


That is the whole piont I am not understanding.

I thought there should only be one DNS server running at a central location
Click to expand...


No, there are many. I assume that they somehow communicate with each
other, so that they all contain essentially the same information, but
I don't know the specifics of how that is done.

which maps names to ip addresses(and all the requests regarding which ISP's
they are from should go to that server). Regardless there should be only
central database which maps domain names to ip addresses. Please share your
thoughts.

Thnx.
Click to expand...
 
"Every" is a very strong word that I'm always reluctant to use. I
wouldn't be surprised if some don't and share another ISP's server.
Still the answer to your question is generally yes.
Click to expand...

That's not quite how I understand it. In general, there's a DNS (Domain
Name Server) that tells you which DNS handles ".com" and which one
handles ".net" and so on.
So to lookup www.swiftys.org.uk you start with the ".uk" piece, then go
to the DNS for the '.org.uk' piece and so on. Eventually you ask the DNS
for "swiftys.org.uk" what the IP address of "www.swiftys.org.uk" is, and
you have the IP address of my webserver. (Or rather the IP address of my
friends Linux server, which hosts my website in his garage).

There are shortcuts built into the mechanism, and it's a *lot* more
complex than I've indicated.

My ISP is BT, and they have a DNS for their own IP addresses, which I
use, but when resolving "www.swiftys.org.uk" it gets it from somewhere
completely different, and even though I'm paying someone for this
service, I don't really have much idea how it works.
 
Swifty said:
That's not quite how I understand it. In general, there's a DNS (Domain
Name Server) that tells you which DNS handles ".com" and which one handles
".net" and so on.
So to lookup www.swiftys.org.uk you start with the ".uk" piece, then go to
the DNS for the '.org.uk' piece and so on. Eventually you ask the DNS for
"swiftys.org.uk" what the IP address of "www.swiftys.org.uk" is, and you
have the IP address of my webserver. (Or rather the IP address of my
friends Linux server, which hosts my website in his garage).

There are shortcuts built into the mechanism, and it's a *lot* more
complex than I've indicated.

My ISP is BT, and they have a DNS for their own IP addresses, which I use,
but when resolving "www.swiftys.org.uk" it gets it from somewhere
completely different, and even though I'm paying someone for this service,
I don't really have much idea how it works.
Click to expand...

DNS is basically hierarchal. What happens is this. Say when you type in
www.microsoft.com. It will first check your hosts and lmhosts files on the
local machine. If it does not find it there, it next checks the dns servers
indicated when you get your ip address from your ISP through DHCP, or
whatever you entered if you have a static IP. Simplistically put, it will
keep kicking the the request up the line until it gets to the root servers
if needed until the address of the site requested is found.

I could get into a more technical explanation as to how the root servers
pass off to authoritative servers at the top level domains( .com, .edu,
..org, etc.), why caching is important in relation to speed, ad nauseam. But
this just gives you the basics of how things work.
 
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