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What's the logic in IP-numbers?
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Well, what the numbers mean vary upon what class IP address it is (Class A, B, or C. I think there are also classes D and E, but I honestly don't know much, if anything about them.)
Class A addresses look like this:
N.H.H.H
with the N standing for Network, and the H standing for Host.
Class B:
N.N.H.H
Class C:
N.N.N.H
You can identify what class the IP address is by looking at the first octet (an octet is just a technical way of saying each section seperated by a dot). IP addresses whose first octet ranges anywhere from 0 to 127 is a class A address, IP addresses whose first octet ranges from 128 to 191 is a class B address, and any address that ranges from 192 to 233 are class c.
IP's aren't very easy to understand, at least in detail. The only reason I know anything on them (and there's a helluva lot I don't know about them still) is because I'm taking a cisco networking class at school, and a lot of the stuff we did in the first semester involved IP's (subnetting, DNS, ARP, crap like that).
But this page might help you out some in more information about IP's:
http://www.zdwebopedia.com/TERM/I/IP_address.html
Whois is a great way to read an ip adress or a DNS query
for some more ifo check out RFC1112 (read it a couple of times its kinda dry)
A host that is connected to the net must have an IP address, so it can be identified,
and information can be relayed and routed to it in an orderly fashion.
an IP address consists of a 32 bit logical address. The address is divided
into two fields:
1) The network address:
Assigned by InterNIC (Internet Network Information Center).
In fact most ISPs (internet service providers) purchase a number of addresses
and assign them individually.
2) The station address:
An address that identifies the station throughout the network. It is assigned
by the network manager (administrator).
IP address structure:
---.---.---.---
======= +++++++
^ ^
| |
network | station.
Every " --- " = 8 bits.
The first 16 ===> netwrok address
The last 16 ===> station address
with 8 bits you can present from 0-255 . (binary=(2 to the power of 8)-1)
Example:
11000010.01011010.00011111.01001010 (binary)
194.90.31.74 (decimal)
IP address CLASSES :
We can classify IP addreses to 5 groups. You can distinguish them by comparing
the "High Order" bits (the first four bits on the left of the address):
type | model | target | MSB |addr.range |bit number| max.stations|
| | groups | | |net./stat.| |
------|--------|--------|-----|--------------|----------|-------------|
A |N.S.S.S | ALL | 0 | 1.0.0.0 | 24/7 | 16,777,214 |
| | ACCEPT | | to | | |
| | HUGE | | 126.0.0.0 | | |
| | CORPS | | | | |
-----------------------------------------------------------------------
|N.N.S.S | TO ALL | 10 | 128.1.00 | 16/14 | 65,543 |
B | | LARGE | | to | | |
| | CORPS | | 191.254.00 | | |
-----------------------------------------------------------------------
|N.N.N.S |TO ALOT | 110 | 192.0.1.0 | 8/22 | 254 |
C | |OF | | to | | |
| |SMALL | | 223.225.254 | | |
| |CORPS | | | | |
-----------------------------------------------------------------------
D | NONE |MULTI-CA|1110 | 224.0.0.0 | NOT FOR | UNKNOWN |
| |ST ADDR.| | to | USUAL | |
| |RFC-1112| |239.255.255.255| USE | |
-----------------------------------------------------------------------
E | NOT FOR|EXPERIME|1,1,1,1| 240.0.0.0 |NOT FOR| NOT FOR USE|
| USE |NTAL | | to |USE | |
| |ADDR. | |254.255.255.255| | |
-----------------------------------------------------------------------
N=NETWORK , S=STATION .
As you can see in the table above the address range 127.X.X.X is not in use.
These addresses are assigned to internal use to the network device, and are
used as an application tool only. For example: 127.0.0.1, the most common one,
is called the loopback address - everything sent here goes directly back to
you, without even traveling out of the wire.
Also, some IPs are reserved for VPNs - Virtual Private Networks. These are
local area networks or wide area networks that use the Internet Protocol to
communicate, and each computer inside the network is assigned with an IP
address. So, suppose a certain computer wants to send a data packet to
another host on the network with the IP 'x', but there's also another host on
the Internet that has the same IP - what happens now? So this is why you
cannot use these and other forms of reserved IPs on the Internet.
EXTRA:
Distinguishing different groups:
You have to compare the first byte on the left in the address as follows:
Type | First byte | MSB
| in decimal |
----------------------------
A | 1-126 | 0
----------------------------
B | 128-191 | 10
----------------------------
C | 192-223 | 110
----------------------------
D | 224-254 | 1110
----------------------------
E | 240-254 | 1111
for some more ifo check out RFC1112 (read it a couple of times its kinda dry)
A host that is connected to the net must have an IP address, so it can be identified,
and information can be relayed and routed to it in an orderly fashion.
an IP address consists of a 32 bit logical address. The address is divided
into two fields:
1) The network address:
Assigned by InterNIC (Internet Network Information Center).
In fact most ISPs (internet service providers) purchase a number of addresses
and assign them individually.
2) The station address:
An address that identifies the station throughout the network. It is assigned
by the network manager (administrator).
IP address structure:
---.---.---.---
======= +++++++
^ ^
| |
network | station.
Every " --- " = 8 bits.
The first 16 ===> netwrok address
The last 16 ===> station address
with 8 bits you can present from 0-255 . (binary=(2 to the power of 8)-1)
Example:
11000010.01011010.00011111.01001010 (binary)
194.90.31.74 (decimal)
IP address CLASSES :
We can classify IP addreses to 5 groups. You can distinguish them by comparing
the "High Order" bits (the first four bits on the left of the address):
type | model | target | MSB |addr.range |bit number| max.stations|
| | groups | | |net./stat.| |
------|--------|--------|-----|--------------|----------|-------------|
A |N.S.S.S | ALL | 0 | 1.0.0.0 | 24/7 | 16,777,214 |
| | ACCEPT | | to | | |
| | HUGE | | 126.0.0.0 | | |
| | CORPS | | | | |
-----------------------------------------------------------------------
|N.N.S.S | TO ALL | 10 | 128.1.00 | 16/14 | 65,543 |
B | | LARGE | | to | | |
| | CORPS | | 191.254.00 | | |
-----------------------------------------------------------------------
|N.N.N.S |TO ALOT | 110 | 192.0.1.0 | 8/22 | 254 |
C | |OF | | to | | |
| |SMALL | | 223.225.254 | | |
| |CORPS | | | | |
-----------------------------------------------------------------------
D | NONE |MULTI-CA|1110 | 224.0.0.0 | NOT FOR | UNKNOWN |
| |ST ADDR.| | to | USUAL | |
| |RFC-1112| |239.255.255.255| USE | |
-----------------------------------------------------------------------
E | NOT FOR|EXPERIME|1,1,1,1| 240.0.0.0 |NOT FOR| NOT FOR USE|
| USE |NTAL | | to |USE | |
| |ADDR. | |254.255.255.255| | |
-----------------------------------------------------------------------
N=NETWORK , S=STATION .
As you can see in the table above the address range 127.X.X.X is not in use.
These addresses are assigned to internal use to the network device, and are
used as an application tool only. For example: 127.0.0.1, the most common one,
is called the loopback address - everything sent here goes directly back to
you, without even traveling out of the wire.
Also, some IPs are reserved for VPNs - Virtual Private Networks. These are
local area networks or wide area networks that use the Internet Protocol to
communicate, and each computer inside the network is assigned with an IP
address. So, suppose a certain computer wants to send a data packet to
another host on the network with the IP 'x', but there's also another host on
the Internet that has the same IP - what happens now? So this is why you
cannot use these and other forms of reserved IPs on the Internet.
EXTRA:
Distinguishing different groups:
You have to compare the first byte on the left in the address as follows:
Type | First byte | MSB
| in decimal |
----------------------------
A | 1-126 | 0
----------------------------
B | 128-191 | 10
----------------------------
C | 192-223 | 110
----------------------------
D | 224-254 | 1110
----------------------------
E | 240-254 | 1111
it gets different for subnets n stuff. here is a bit about how it all works (you proably know most of it, its a bit simple)BTW DNS= Domain Name Server
like robin said a hostname is just an alias for an ip #.
A DNS is basically a resource for converting friendly Hostnames (like hotmail.com)which humans can easily
understand, into IP addresses which machines need to communicate to the host i.e. hotmail.com. Now what basically happens in that when you type http://www.hotmail.com in the location bar of your browser, the browser needs to perform a lookup to find the machine readable IP address so
that it can communicate with the host.This means that the browser cannot communicate with a host if it
has the friendly hostname only.
Without the IP address, no communication can take place. So for the lookup,the browser contacts the DNS server setup by normally by your ISP and through the resolver tries to look
for the IP conversion of the hostname the user wants to contact.
A DNS server is basically a server running DNS software.The server that the browser first looks for a translation is the Primary DNS server, if this primary server doesn't show
any match then this server contacts another DNS server somewhere on the Internet (This becomes the Secondary
DNS Server.)and looks for a match. If a match is found in the secondry server then the Primary server updates it's database so that it doesn't have to contact the Secondry server again for the same match.Each DNS server stores
the hosts it has recently looked for in it's cache. Now if the Server has recently looked for a particular
hostname, then it does not search for it again but just provides the browser with that information from it's
cache. If the cache does not contain a particular entry, then the resolver looks for the desired entry by searching through the entire database.
New techologies are being introduced in the DNS sphere. Now take the case of amazon.com. It is a famous and large E-company with over a million users per day.(My rough estimate.)Such large organizations have multiple IP addresses for the same domain name. Today what happens is that the DNS server returns all IP Addresses and the browser chooses a random IP from it. But this new technolofy
will allow the DNS server to return the IP of the server which has the least trafiic, so as to enhanse surfing. So you can see DNS does make sense.
You can see how time consuming the above process can be and it can really slow down your surfing process, a lot of time is being wasted when the browser contacts the DNS server
and performs a lookup, so how do you fasten this process? How do you eliminate the fact that the browser will contact the DNS server each time you want to visit a site? Well the answer lies in the HOSTS file hidden in the c:\windows directory.
You can map a machine's IP to any hostname by editing the c:\windows\hosts file(It has no extension.)on win 9.x systems, On NT the hosts file is c:\WinNT\system32\drivers\etc\hosts and on Linux it is /etc/hosts.(i think)
A hosts file looks something like the below:
###############################
# Copyright (c) 1998 Micro$oft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP stack for Windows98
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.xx.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
1. localhost
#####################################
For example, if you know that the IP address of say hotmail.com is 207.xxx.xxx.xxx., then if you add the
following in the Hosts file then the browser will not perform a lookup and
will
starighaway have the IP to
communicate with the host. So add the line:
207.xxx.xxx.xxx http://www.hotmail.com
Now your browser will connect faster to Hotmail.com. This technique can increase your surfing speed tremendously.(if your a hardcore geek) So now that you know what a DNS is...
heh.
like robin said a hostname is just an alias for an ip #.
A DNS is basically a resource for converting friendly Hostnames (like hotmail.com)which humans can easily
understand, into IP addresses which machines need to communicate to the host i.e. hotmail.com. Now what basically happens in that when you type http://www.hotmail.com in the location bar of your browser, the browser needs to perform a lookup to find the machine readable IP address so
that it can communicate with the host.This means that the browser cannot communicate with a host if it
has the friendly hostname only.
Without the IP address, no communication can take place. So for the lookup,the browser contacts the DNS server setup by normally by your ISP and through the resolver tries to look
for the IP conversion of the hostname the user wants to contact.
A DNS server is basically a server running DNS software.The server that the browser first looks for a translation is the Primary DNS server, if this primary server doesn't show
any match then this server contacts another DNS server somewhere on the Internet (This becomes the Secondary
DNS Server.)and looks for a match. If a match is found in the secondry server then the Primary server updates it's database so that it doesn't have to contact the Secondry server again for the same match.Each DNS server stores
the hosts it has recently looked for in it's cache. Now if the Server has recently looked for a particular
hostname, then it does not search for it again but just provides the browser with that information from it's
cache. If the cache does not contain a particular entry, then the resolver looks for the desired entry by searching through the entire database.
New techologies are being introduced in the DNS sphere. Now take the case of amazon.com. It is a famous and large E-company with over a million users per day.(My rough estimate.)Such large organizations have multiple IP addresses for the same domain name. Today what happens is that the DNS server returns all IP Addresses and the browser chooses a random IP from it. But this new technolofy
will allow the DNS server to return the IP of the server which has the least trafiic, so as to enhanse surfing. So you can see DNS does make sense.
You can see how time consuming the above process can be and it can really slow down your surfing process, a lot of time is being wasted when the browser contacts the DNS server
and performs a lookup, so how do you fasten this process? How do you eliminate the fact that the browser will contact the DNS server each time you want to visit a site? Well the answer lies in the HOSTS file hidden in the c:\windows directory.
You can map a machine's IP to any hostname by editing the c:\windows\hosts file(It has no extension.)on win 9.x systems, On NT the hosts file is c:\WinNT\system32\drivers\etc\hosts and on Linux it is /etc/hosts.(i think)
A hosts file looks something like the below:
###############################
# Copyright (c) 1998 Micro$oft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP stack for Windows98
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.xx.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
1. localhost
#####################################
For example, if you know that the IP address of say hotmail.com is 207.xxx.xxx.xxx., then if you add the
following in the Hosts file then the browser will not perform a lookup and
will
starighaway have the IP to
communicate with the host. So add the line:
207.xxx.xxx.xxx http://www.hotmail.com
Now your browser will connect faster to Hotmail.com. This technique can increase your surfing speed tremendously.(if your a hardcore geek) So now that you know what a DNS is...
heh.
Gayowulf:
Whattalota information!!
It seems like you copied all that material in your first post from somewhere else, but did you copy or write yourself your second post? 'cause there are some spelling mistakes there... if you did write it yourself (likely), then, um, good work. I never knew that you can do that with the hosts file. Maybe I'll try it out someday...
BTW, the next time you want to post something like your first post, enclose it all in a [ CODE ] tag, something I learned from my other posts.
Whattalota information!!
It seems like you copied all that material in your first post from somewhere else, but did you copy or write yourself your second post? 'cause there are some spelling mistakes there... if you did write it yourself (likely), then, um, good work.
I never knew that you can do that with the hosts file. Maybe I'll try it out someday...BTW, the next time you want to post something like your first post, enclose it all in a [ CODE ] tag, something I learned from my other posts.
