Numeric URLs

[Dennis Marks]

I believe that addresses in the form aaa.bbb.ccc are converted by
address servers to the form nnn.nnn.nnn.nn. Does that mean that there
is a numeric URL for every alpha URL? I used NSLOOKUP to find out the
numeric form of the address of my isp. The numeric version gave me the
server default page (just a dummy that should be changed) rather than
the actual home page of the isp.

The reason that I ask is when an alpha address is used it must go
thought an address server to be converted. Would a link on a web page
be faster if the actual numeric address was used? What if the address
server was down? Could the numeric form bypass it?

 

[brucie]

in post: <

I believe that addresses in the form aaa.bbb.ccc are converted by
address servers to the form nnn.nnn.nnn.nn.
yes

Does that mean that there is a numeric URL for every alpha URL?

no. theres not enough numbers in IPv4 to do that.

I used NSLOOKUP to find out the numeric form of the address of my isp.
The numeric version gave me the server default page (just a dummy
that should be changed) rather than the actual home page of the isp.

it depends on how the server is setup on what gets returned to the
visitor.

The reason that I ask is when an alpha address is used it must go
thought an address server to be converted.

its called a domain name server
http://computer.howstuffworks.com/dns.htm

Would a link on a web page be faster if the actual numeric address was
used?

not worth the effort for the miniscule time for the lookup and
unreliable.

What if the address server was down? Could the numeric form bypass it?

yes. worth a try if your ISPs DNS is unreliable but the majority of the
time you'll just end up on a default page for the server, not for a
particular site on that server as the sites are probably sharing the
same IP.

 

[David Dorward]

I believe that addresses in the form aaa.bbb.ccc are converted by
address servers to the form nnn.nnn.nnn.nn. Does that mean that there
is a numeric URL for every alpha URL?

Yes, but not a unique one.

I used NSLOOKUP to find out the
numeric form of the address of my isp. The numeric version gave me the
server default page (just a dummy that should be changed) rather than
the actual home page of the isp.

Webservers are generally configured with a default site, and then with a
specific site for different host names. Look up Virtual Name Hosting in the
Apache manual.

The reason that I ask is when an alpha address is used it must go
thought an address server to be converted. Would a link on a web page
be faster if the actual numeric address was used?

Yes, but not significantly.

What if the address server was down? Could the numeric form bypass it?

Yes, so long as it was the default site for the server.

 

[Richard]

I believe that addresses in the form aaa.bbb.ccc are converted by
address servers to the form nnn.nnn.nnn.nn. Does that mean that there
is a numeric URL for every alpha URL? I used NSLOOKUP to find out the
numeric form of the address of my isp. The numeric version gave me the
server default page (just a dummy that should be changed) rather than
the actual home page of the isp.

The reason that I ask is when an alpha address is used it must go
thought an address server to be converted. Would a link on a web page
be faster if the actual numeric address was used? What if the address
server was down? Could the numeric form bypass it?

You do not need a domain name to be online.
Domain names were created because they are easier to remember.
An IP merely points to a specific machine.
Within that IP could be numerous domain names.

As an example of your question try this:

www.1-large-world.com
http://66.246.88.70

Both take you to the same site don't they?
But what if I had other domains on that same IP?
How would you resolve an IP to that one particular name?

As you surmise, the numeric is faster loading than the alpha because there
is no name server or lookup involved.
This may be useful for those using slow dialup, but on faster systems the
difference is hardly noticable.

 

[SpaceGirl]

I believe that addresses in the form aaa.bbb.ccc are converted by
address servers to the form nnn.nnn.nnn.nn. Does that mean that there
is a numeric URL for every alpha URL? I used NSLOOKUP to find out the
numeric form of the address of my isp. The numeric version gave me the
server default page (just a dummy that should be changed) rather than
the actual home page of the isp.

The reason that I ask is when an alpha address is used it must go
thought an address server to be converted. Would a link on a web page
be faster if the actual numeric address was used? What if the address
server was down? Could the numeric form bypass it?

We bought two IP addresses (xxx.xxx.xxx.xxx) which resolve to about 30
domains.

blah.com > 123.123.123.123
poo.com > 123.123.123.123
abc.com > 123.123.123.123

our web server is at the address 123.123.123.123, and all domains resolve
there. The server reads the header (www.blah.com, for example) and uses this
to load the correct web site from all of those hosted on that machine. This
happens instantly, and there's no real impact on server performance or the
time it takes for a site to resolve. If you typed in the IP address itself
(123.123.123.123) in your browser, you'd get the "root site" on our server,
not any of the other sites hosted on it.

 

[Dennis Marks]

We bought two IP addresses (xxx.xxx.xxx.xxx) which resolve to about 30
domains.

blah.com > 123.123.123.123
poo.com > 123.123.123.123
abc.com > 123.123.123.123

our web server is at the address 123.123.123.123, and all domains resolve
there. The server reads the header (www.blah.com, for example) and uses this
to load the correct web site from all of those hosted on that machine. This
happens instantly, and there's no real impact on server performance or the
time it takes for a site to resolve. If you typed in the IP address itself
(123.123.123.123) in your browser, you'd get the "root site" on our server,
not any of the other sites hosted on it.

My web site is http://www.dcs-chico.com/~denmarks/
NSLOOKUP shows www.dcs-chico.com as 209.232.199.10
How come http://209.232.199.10/~denmarks/ doesn't work?

 

[Deirdre Saoirse Moen]

My web site is http://www.dcs-chico.com/~denmarks/
NSLOOKUP shows www.dcs-chico.com as 209.232.199.10
How come http://209.232.199.10/~denmarks/ doesn't work?

In small words:

There is not a one-to-one correspondence between numbers and addresses.
A single IP can serve many domains.
A single server (www.apple.com) can resolve to many numbers.

This has been explained already.

Use the names and forget about the numbers.

 

[SpaceGirl]

My web site is http://www.dcs-chico.com/~denmarks/
NSLOOKUP shows www.dcs-chico.com as 209.232.199.10
How come http://209.232.199.10/~denmarks/ doesn't work?

Because that IP address (209.232.199.10) is the address of the server, not
your web site.

Imagine it like this; an IP address (209.232.199.10) is the number of your
building. Someone sends a postcard to your apartment. Now, each apartment in
that building is referred to by name (www.fredblogs.com), and at the front
door of your building there is an attendant who makes sure the right mail
goes to the right apartments. When someone sends that postcard, they only
know the address of your building, not your actual apartment.

Okay back in the less confusing real world; The IP address (209.232.199.10)
is the physical address of the computer hosting your web site on the
internet. It might be hosting 1000s of other web sites. When someone types
in your web address, that name is translated into the IP address and sent
along with the complete name (www.whatever.com) to the destination web
server. Now that web server sees the name attached in the HTTP headers and
says "ah, you mean this web site in this folder" and sends a reply back to
the users web browser with the correct page/data/whatever. The header
information is the important bit - it's the bit that set your site apart
from all the other hundreds of web sites also hosted on that single physical
IP address. So, if you type in the IP address that your web site *looks*
like it's on into a browser, it's not necessarily yours alone, so you may
not get any web site at all. Often hosts will place their own web site so
that it loads whenever an IP address is used and no header is sent with a
'what' web site is supposed to be show. In other words, it defaults to their
own site.

One of our web sites is www.subhuman.net. The physical IP of the machine it
is hosted on is 66.245.184.192. Try typing that number into a web browser
and you'll find there's no site there. That's because it's a shared box,
with some 200 other clients on it. We didn't bother setting up a default
site.

Now someone will shoot me for getting funky with HTTP, but I'm trying to
keep it simple

 

[Dennis Marks]

Because that IP address (209.232.199.10) is the address of the server, not
your web site.

Imagine it like this; an IP address (209.232.199.10) is the number of your
building. Someone sends a postcard to your apartment. Now, each apartment in
that building is referred to by name (www.fredblogs.com), and at the front
door of your building there is an attendant who makes sure the right mail
goes to the right apartments. When someone sends that postcard, they only
know the address of your building, not your actual apartment.

Okay back in the less confusing real world; The IP address (209.232.199.10)
is the physical address of the computer hosting your web site on the
internet. It might be hosting 1000s of other web sites. When someone types
in your web address, that name is translated into the IP address and sent
along with the complete name (www.whatever.com) to the destination web
server. Now that web server sees the name attached in the HTTP headers and
says "ah, you mean this web site in this folder" and sends a reply back to
the users web browser with the correct page/data/whatever. The header
information is the important bit - it's the bit that set your site apart
from all the other hundreds of web sites also hosted on that single physical
IP address. So, if you type in the IP address that your web site *looks*
like it's on into a browser, it's not necessarily yours alone, so you may
not get any web site at all. Often hosts will place their own web site so
that it loads whenever an IP address is used and no header is sent with a
'what' web site is supposed to be show. In other words, it defaults to their
own site.

Let me see if I understand.
209.232.199.10 is the address of the server.
My isp is the domain www.dcs-chico.com.
There can be other domains www.xxx.com on the same server.
Even though I state /~denmarks./ the server has no idea if it is part
of www.dcs-chico.com or www.xxx.com.

 

[brucie]

in post: <

Let me see if I understand.
209.232.199.10 is the address of the server.
My isp is the domain www.dcs-chico.com.
There can be other domains www.xxx.com on the same server.
Even though I state /~denmarks./ the server has no idea if it is part
of www.dcs-chico.com or www.xxx.com.

the server isn't configured to return your site using
http://209.232.199.10/~denmarks/ simple. probably because of the www.
the server is also miss configured and returns http response header
codes that don't exist.

 

[SpaceGirl]

Let me see if I understand.
209.232.199.10 is the address of the server.
My isp is the domain www.dcs-chico.com.
There can be other domains www.xxx.com on the same server.
Even though I state /~denmarks./ the server has no idea if it is part
of www.dcs-chico.com or www.xxx.com.

Exactly.

Sites can also fail (as Brucie suggests) when the webmaster 'forgets' to
add the "www" in the header for your domain. So http://mysite.com would
work, but http://www.mysite.com would not. The "www" is part of the header
just like anything else. If you have ever seen "ww2.something.com", this is
because those first three characters in a domain name can actually be
anything at all. Example, one of our commerical servers has the domain
staging.something.net while the live site is www.something.net. Both are on
the same physical box, but they are actually two different sites, giving the
illusion that one is part of the other.

 

[David Dorward]

If you have ever seen "ww2.something.com", this
is because those first three characters in a domain name can actually be
anything at all.

Including a number of characters other then 3

Example, one of our commerical servers has the domain
staging.something.net

such

And you can go as many levels as you like.

www.staging.extranet.dorward.me.uk could exist quite happily had I the need
for it.

 

[Toby A Inkster]

www.staging.extranet.dorward.me.uk could exist quite happily had I the need
for it.

Just for fun...
http://a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.goddamn.co.uk/