LQWiki - User contributions [en]

Imap

2006-07-21T20:01:18Z

Osor: redirect to IMAP

#REDIRECT[[IMAP]]

Pop

2006-07-21T20:00:29Z

Osor: added redirect to POP3

#REDIRECT[[POP3]]

Subnet mask

2006-07-21T19:49:58Z

Osor:

A '''subnet mask''' is used in the IP addressing system which divides the [[IP address]] in two parts: the [[Subnet|network part]] and the [[host bits|host part]]. A subnet mask (also shortened to '''netmask''') is usually expressed like an IP address in [[dotted decimal]] notation. The subnet mask works by ''masking out'' the network part from the full [[IP address]]:

The logical operation AND is performed with the IP address and netmask.
192.168.3.45 AND 255.255.255.0 = 192.168.3.0
This tells us that the computer with an address of 192.168.3.45 belongs to a [[Subnet|subnet]] called 192.168.3.0.

==See also==
* [[Subnet]]
* [http://www.subnetmask.info www.subnetmask.info] for [[IPv4]] subnet mask calculators

{{stub}}

[[Category:Networking]]

Subnet mask

2006-07-21T19:49:14Z

Osor:

A '''subnet mask''' is used in the IP addressing system which divides the [[IP address]] in two parts: the [[Subnet|network part]] and the [[host bits|host part]]. A subnet mask (also shortened to '''netmask''') is usually expressed like an IP address in [[dotted decimal]] notation. The subnet mask works by ''masking out'' the network part from the full [[IP address]]:

The logical operation AND is performed with the IP address and netmask.
192.168.3.45 AND 255.255.255.0 = 192.168.3.0
This tell us that the computer with an address of 192.168.3.45 belongs to a [[Subnet|subnet]] called 192.168.3.0.

==See also==
* [[Subnet]]
* [http://www.subnetmask.info www.subnetmask.info] for [[IPv4]] subnet mask calculators

{{stub}}

[[Category:Networking]]

Netmask

2006-07-21T19:31:41Z

Osor:

#REDIRECT[[Subnet_mask]]

CIDR notation

2006-07-06T03:36:37Z

Osor:

The canonical way of conveying the identity a network is to specify an [[IP address]] and a [[subnet mask]]. The problem with this method is that the netmask is in [[dotted decimal]] notation, yet the ''mask'' operates in a bitwise fashion. This means that only select few decimal digits can be used in a the fields of a netmask (for example 255.255.253.0 is an invalid netmask). The correct usage of the netmask therefore requires either
*Memorization of the most commonly seen forms (comes with experience)
*Fluency in binary (comes with a whole lot of experience)
*Having a reference table/calculator handy

[[CIDR]] notation is the abbreviation of an [[IP address]] and [[subnet mask]] using the number of bits used for the subnet appended to the end of the IP address, thus:

CIDR: 192.168.0.0/24
''is an abbreviation for:''
IP Address: 192.168.0.0
Netmask: 255.255.255.0
(in binary) 11111111.11111111.11111111.00000000
''because this subnet mask uses 24 bits for the network portion of the address.''

'''Another example:'''
CIDR: 192.168.0.0/21
''would look like:''
IP Address: 192.168.0.0
Netmask: 255.255.248.0
(in binary) 11111111.11111111.11111000.00000000
And so on...

Because of its versatility, brevity, and easiness to understand CIDR notation is now the preferred method of identifying a network.

==See also==
*[[subnetting]]
*[[supernetting]]

User:Osor

2006-07-06T00:19:18Z

Osor:

You have reached Osor's page. This is probably a mistake. Osor probably doesn't interest you much.

Talk:Subnet mask

2006-07-06T00:18:01Z

Osor: typo

I'm thinking the information on this page is already explained much better in [[Subnet]]. Would it be a good idea to get rid of this page (i.e., redirect)? I'll give it a few days before taking action.
--[[User:Osor|Osor]] 17:29, July 5, 2006 (EDT)
:A subnet and a subnet mask are really two different topics IMHO, so they should probably be distinct articles (current content aside). At a minimum, I'd say if they are combined, a subnet mask section should be added to the subnet page. [[User:Jeremy|Jeremy]] 19:39, July 5, 2006 (EDT)
::Of course they are two different topics. What I'm saying is that the [[Subnet]] page already has a (much better) explanation of subnet masks. Rather than reinvent the wheel here (on [[Subnet mask]]), I wanted to reduce data duplication. There are many ways to do this
::#Move the bulk of the subnet mask information from [[Subnet]] to here, and add an obvious link
::#Get rid of this page entirely, and reorganize [[Subnet]] to have a subsection for subnet mask
::#Make this page redirect to [[Subnet]]
::I'm not saying the last way is the best, but it certainly is the easiest. --[[User:Osor|Osor]] 20:17, July 5, 2006 (EDT)

Talk:Subnet mask

2006-07-06T00:17:21Z

Osor:

I'm thinking the information on this page is already explained much better in [[Subnet]]. Would it be a good idea to get rid of this page (i.e., redirect)? I'll give it a few days before taking action.
--[[User:Osor|Osor]] 17:29, July 5, 2006 (EDT)
:A subnet and a subnet mask are really two different topics IMHO, so they should probably be distinct articles (current content aside). At a minimum, I'd say if they are combined, a subnet mask section should be added to the subnet page. [[User:Jeremy|Jeremy]] 19:39, July 5, 2006 (EDT)
::Of course they are two different topics. What I'm saying is that the [[Subnet]] page already has a (much better) explanation of subnet masks. Rather than reinvent the wheel here (on [[Subnet mask]]), I wanted to reduce data duplication. There are many ways to do this
::#Move the bulk of the subnet mask information from [[Subnet]] to here, and add an obvious ::link
::#Get rid of this page entirely, and reorganize [[Subnet]] to have a subsection for subnet mask
::#Make this page redirect to [[Subnet]]
::I'm not saying the last way is the best, but it certainly is the easiest. --[[User:Osor|Osor]] 20:17, July 5, 2006 (EDT)

Subnet

2006-07-06T00:07:19Z

Osor: /* Determining the network address */

All computers on the same network can directly send packets to eachother. When one sends a broadcast packet, all the rest get that packet (that is to say, they're all on the same "broadcast domain" -- aka "VLAN").

Routers connect networks together.

Typcially, a bunch of computers connected to eachother in one room form a network. Also typical is to assign them rfc1918 "reserved" addresses (look up that RFC for more info on those special IP addresses). Perhaps one computer on that network connects that network to the rest of the internet -- this computer is the so-called "gateway". It's performing routing, and is a router. Note, it's configured to not forward packets addressed to an rfc1918 address.

A '''subnet''' is a network, and is the set of all [[network interface]]s which have the same network address. You usually have one subnet per VLAN. If a machine on that subnet needs to talk to another machine on the subnet, it delivers the packet directly. Packets destined for other machines need to go through the gateway.

== Determining the network address ==

To determine the network address we use a subnet mask, or "netmask". This is a [[binary]] number that is used to "mask" an IP address into network and host address portions.

For example, an [[IPv4]] [[IP address]] and subnet mask are both 32 bits long. Take an address such as:

209.152.163.16

In binary this is:

11010001 10011000 10100011 00010000

The subnet mask is given as either a [[dotted decimal]] or in [[CIDR notation]] (using a bit count). For example, the [[Network Class|Class B]] subnet mask is:

255.255.0.0

In binary this is

11111111 11111111 00000000 00000000

i.e. a string of 16 1's, followed by 0's. The [[CIDR]] representation is given as a forward-slash followed by the number of 1's:

/16

It is often appended to the end of the IP address.

209.152.163.16/16

The subnet mask is used to determine the network and host portions of an [[IP address]] in the following ways:

To determine the network address, apply a [[binary]] AND operation to the IP address and the subnet mask:

<pre>
11010001 10011000 10100011 00010000
11111111 11111111 00000000 00000000
-----------------------------------
11011001 10011000 00000000 00000000
</pre>

Converting this back to [[dotted decimal]] gives us a network address of:

209.152.0.0

All [[network interface]]s and computers that have this network address can be said to share the same subnet.

==More complex subnets==
Whilst this is a fairly trivial example, more complex subnets can be created by using a subnet mask that does not end on a margin between [[dotted decimal]] numbers.

A subnet mask of:

11111111 11111111 11100000 00000000

is

255.255.224.0

in [[dotted decimal]], or

/19

as a bit count. This type of subnetting is usually done by network administrators to create a number of subnetworks within a single class.

==See also==
*[[Networking basics]]

Network addressing

2006-07-06T00:05:18Z

Osor: /* Subnet Masks */

==IP Adressing==
===IPv4 - The current Internet standard===
To connect to an IP network, your host (specifically your host's [[network interface]]) will need a unique [[IP address]] to identify itself as a host on the network. In IPV4, an IP address is a 32-bit number that uniquely identifies your [[NIC]] on a network. For ease of readability we divide this 32-bit number into 4 [[octet]]s with a period separating each one. Each octet has a decimal equivalent of 0-255. A typical IP address then would look something like this: 192.168.5.26.

===Assigning IP Address===
There are two ways to set the IP address for a [[NIC]]. You can do it manually or you can have it set automatically via [[DHCP]]. [[DHCP]] dynamically assigns IP addresses and other information such as [[subnet mask]], [[DNS]] server, and [[default gateway]] to hosts upon bootup. Most network routers have DHCP built in and enabled by default. However, for small networks it may be preferable to set the IP address manually.

===Subnet Masks===
[[subnet mask|Subnet masks]] also known as network masks are used to logically split a network into "subnetworks".

When the IP address scheme was originally designed, there were three [[Network Class]]es: Class "A", which had 126 networks of 16 million addresses in each network, Class "B" which had about 65,000 networks of 65,634 addresses in each network, and Class "C" networks which were millions of networks of 254 addresses each. You could tell what kind of network you were on by looking at the first byte of the IP address: 1-126 was class A, 128 to 192 was class "B", and 129 to 192 was class "C". (193 to 254 are reserved for special purposes).

The problem with this scheme is that it is too inflexible. You might need only 2 addresses on a network. So the subnet mask was invented, to give the network designed more control and flexibility.
Simply put, a subnet mask describes what portion (that is, which bits) of an address describes which logical network (the subnet) a host belongs to, and what portion identifies the host on that network. (Note: all hosts/devices on your local network must share the same subnet if you want them to able to communicate, otherwise the use of [[routing]] will be necessary.).

So, for example, suppose I need a network with a single machine on it. I need a second IP address on the default router for that network. I also will need an IP address for multicasting. So I can use an IP address of 255.255.255.252. If my IP address is 216.39.145.57, then the network part of my IP address is 216.39.145.56 and the host part of the address is 0.0.0.1. To see how this is done, work in binary.
address 216.39.145.57 11011000.00011011.10010001.00111001
mask 255.255.255.252 11111111.11111111.11111111.11111100
result 216.39.145.56 11011000.00011011.10010001.00111000
My address is 216.39.145.57, the default router or gateway is at 216.39.145.58, and 216.39.145.59 is reserved for multicasting.

Working with strings of bits, e.g. 11111111.11111111.11111111.11111100, is awkward for humans. Working with dotted quads,e.g. 255.255.255.252 is also frequently awkward. So sometimes a network is refered to by its network portion, a slash, and the number of bits in the netmask, e.g. 216.39.145.56/30.

See also: [[Subnet mask]] and [[Network Class]]

==Connecting to the Internet==

An IP address must be unique to your host, which becomes a problem once you connect your machine to the internet. How can you know which IP to choose? In this case an IP address (or range of addresses) must be obtained from your [[ISP]]. An ISP will often assign IP addresses dynamically, giving your computer whichever unique IP address is available from a range it has been assigned. This means your IP address could constantly change, to have a static IP you must ask your ISP to provide you with one however, buying a range of IP addresses can be expensive.

===Private IP Space===
To overcome this there are 3 ranges of address space which have been reserved for private use, and thus are non-routable (they cannot be sent across a [[WAN]]/internet -- a router will refuse to forward packets addressed to these). These are:
'''IP''' - 10.0.0.0 - 10.255.255.255 '''Subnet''' - 255.0.0.0
'''IP''' - 172.16.0.0 - 172.31.255.255 '''Subnet''' - 255.255.0.0
'''IP''' - 192.168.0.0 - 192.168.255.255 '''Subnet''' - 255.255.255.0

===Connecting Multiple Machines===
Since these addresses (sometimes referred to as "private addresses") cannot not be routed to the global Internet, you might ask so how will I connect my hosts with private addresses to the Internet. This is achieved through some tricks:
*[[Router]] with [[NAT|''N''etwork ''A''ddress ''T''ranslation (NAT)]] and [[PAT|''P''ort ''A''ddress ''T''ranslation (PAT)]]. For outgoing packets, NAT will take a private IP address from the internal LAN and replace it with one provided by your [[ISP]]. [[NAT]], as it maps a private address directly to a public address, each host accessing the internet on the internal network must still have a unique public IP. [[PAT]] works around this and can map multiple private addresses to a single private address. This is achieved by assigning each private address a port on which to communicate with the outside world.
*[[Proxy server]] - This is a machine on your network which accepts requests for internet access from the private LAN then masquerades as that machine to the external network.

==Configuring Linux Host==
To set up a Linux machine on a [[network]], you may use the network configuration program that comes with your Linux [[distribution]] (see below), or can do it "by hand". If you do the network configuration "by hand", then you must first be familiar with how Linux references your network interface card ([[NIC]]). Each NIC on a Linux machine is labeled "eth<i>N</i>" where <i>N</i> is and a number, by default the first being 0. Therefore if you have only one [[NIC]] on your machine it will most likely be labeled eth0.
To see a list of settings for your network card use the [[ifconfig]] command (normally you must be [[root]] to run this command).

The IP address can be configured on the command line using ifconfig, the example below configures the device eth0 with IP address 192.168.1.1 and a [[subnet mask]] of 255.255.255.0:
ifconfig eth0 192.168.1.1 255.255.255.0
To have the address dynamically assigned by a [[DHCP]] server on your network with [[hostname]] and [[domain name]] assigned also:
dhcpd -HD eth0

These settings will only apply until your next reboot, different [[distribution]]s have various ways of permanently configuring a computer's [[NIC]].

On some distributions, network configuration information is stored in the /etc/sysconfig directory. On a SuSE system for instance, you will find the network configuration settings in the ifcfg-eth0 file in this directory. This file contains a list of tuples, or key=value pairs, that tell Linux how to configure the eth0 interface. There are many options that can be set in this file but the following example gives the minimal list of required settings:
BOOTPROTO='static'
STARTMODE='onboot'
BROADCAST='192.168.5.255'
IPADDR='192.168.5.178'
NETMASK='255.255.255.0'
NETWORK='192.168.5.0'

In order for changes in this file to take effect, you must restart your interface. You can do this by using the ifdown and ifup commands. So if I have made changes to the eth0 interface I would do the following to restart that interface:
ifdown eth0
ifup eth0
Again, you need to be root to do this.

For a small private network you should use a private address as defined [[#Private IP space|above]]

Many people use "1" (e.g.192.168.1.1) as the final octet for their [[router]] or [[gateway]]. Look at the following example of IP addresses on some made-up [[LAN]]. All netmasks should be 255.255.255.0:
Router: 192.168.1.1
Server 1: 192.168.1.10
Server 2: 192.168.1.11
Print server 1: 192.168.1.50
Print server 2: 192.168.1.51
PC 1: 192.168.1.100
PC 2: 192.168.1.101
PC 3: 192.168.1.102
DHCP Range: 192.168.1.150-200
This gives a general make up that should help define a structured and maintainable network.

===Distribution network configuration programs===
Your distribution probably has a network setup program or programs which make this much easier, and will cover probably 95% of the configurations you will have to do (if it doesn't, then presumably you are sufficiently expert not to need such a program!).

====RedHat Fedora Core====
For example, [[Redhat]] [[Fedora]] Core 4 has four network configuration programs:
* /usr/bin/system-config-network-druid (requires X-windows)
* /usr/bin/system-config-network (requires X-windows)
* /usr/bin/system-config-network-cmd (This is probably best for scripting network configurations)
* /usr/sbin/netconfig (best for command line editing - uses VT-100 style graphics)

====Debian====

====Knoppix====

==See also==

*[[subnetting]]
*[[supernetting]]
*[[IPV6]]
*[[CIDR]]

[[category:Networking]]

Network Class

2006-07-05T23:59:39Z

Osor: /* See Also */

In the early days of [[IP]], networks were delegated in classes. There was no such thing as a [[netmask]] that we use today. Nowadays, however, network classes have become obsoleted by better methods of addressing (such as [[CIDR]]). Nevertheless, learning about network classes can help one's understanding of the [[IPv4]] address-space and how it became the way it has.

In addition to the number of possible hosts on a network, information about the number of possible networks was embedded into the [[IP address]] itself. An address consisted of a ''network part'' and a ''host part''. The network part was itself partitioned to describe the network's class, by the leading number of bits. For each class (decreasing '''A''' through '''E'''), the ''host'' part was in multiples of eight bits (starting from 24 and going 0). The leading bits ''represented'' numbers that were multiples of two (with the exception of '''Class E''' which has four bits representing the number seven), starting from one bit that was zero.

==Examples==
For example, a '''Class A''' network had one leading bit that was necessarily 0. Then, there were 7 bits dedicated to the network. The rest (24 bits) were for hosts. This means that there were only 128 possible Class A networks, each with 24 bits allocatable by the owner. Class A networks were therefore highly sought after and highly limited by the IANA. So any [[IP address]] in the range <tt>0.0.0.0</tt> to <tt>127.255.255.255</tt> was considered as being part of a '''Class A''' network. For example, if someone told you that their [[IP address]] was <tt>93.35.54.123</tt>, you would immediately knew that they were on the Class A network with a first decimal of 93 (in modern [[CIDR notation]], we would call that network <tt>93.0.0.0/8</tt>).

Similarly, any [[IP address]] in the range <tt>128.0.0.0</tt> to <tt>191.255.255.255</tt> was in a '''Class B''' network, and now, there were only 16 bits dedicated to hosts.

For '''Class C''' networks, the range was therefore <tt>192.0.0.0</tt> to <tt>223.255.255.255</tt> with only eight bits dedicated to hosts.

==Special Classes==
Now '''Classes A''', '''B''', and '''C''' described all the normal addresses anyone would use, but there are two more classes.

A '''Class D''' network had a range of <tt>240.0.0.0</tt> to <tt>239.255.255.255</tt>. What makes this unusual is that there are '''zero''' bits dedicated to hosts. How can that be you ask? Well, all '''Class D''' addresses are used only for multicast. This makes sense, as one multicast address can be shared by hosts, and each expects to receive it.

The last network class is '''Class E''', which includes the rest of the address-space (<tt>240.0.0.0</tt> to <tt>255.255.255.255</tt>) and is reserved by the IANA to experimentation.

== See Also ==
*[[CIDR]]
*RFC 791 ([[IP]])
*A lot of RFCs in between
*RFC 1166 (the last RFC to be used for network classes before [[CIDR]] came into effect)

{{stub}}

Talk:Network Class

2006-07-05T23:59:08Z

Osor:

Need to make some sort of table.
Also need to make explanation more understandable.

I know this is not a very high priority for you guys (because classful networks are outdated), but it might be nice to get some review.
--[[User:Osor|Osor]] 19:59, July 5, 2006 (EDT)

Network Class

2006-07-05T23:55:45Z

Osor:

In the early days of [[IP]], networks were delegated in classes. There was no such thing as a [[netmask]] that we use today. Nowadays, however, network classes have become obsoleted by better methods of addressing (such as [[CIDR]]). Nevertheless, learning about network classes can help one's understanding of the [[IPv4]] address-space and how it became the way it has.

In addition to the number of possible hosts on a network, information about the number of possible networks was embedded into the [[IP address]] itself. An address consisted of a ''network part'' and a ''host part''. The network part was itself partitioned to describe the network's class, by the leading number of bits. For each class (decreasing '''A''' through '''E'''), the ''host'' part was in multiples of eight bits (starting from 24 and going 0). The leading bits ''represented'' numbers that were multiples of two (with the exception of '''Class E''' which has four bits representing the number seven), starting from one bit that was zero.

==Examples==
For example, a '''Class A''' network had one leading bit that was necessarily 0. Then, there were 7 bits dedicated to the network. The rest (24 bits) were for hosts. This means that there were only 128 possible Class A networks, each with 24 bits allocatable by the owner. Class A networks were therefore highly sought after and highly limited by the IANA. So any [[IP address]] in the range <tt>0.0.0.0</tt> to <tt>127.255.255.255</tt> was considered as being part of a '''Class A''' network. For example, if someone told you that their [[IP address]] was <tt>93.35.54.123</tt>, you would immediately knew that they were on the Class A network with a first decimal of 93 (in modern [[CIDR notation]], we would call that network <tt>93.0.0.0/8</tt>).

Similarly, any [[IP address]] in the range <tt>128.0.0.0</tt> to <tt>191.255.255.255</tt> was in a '''Class B''' network, and now, there were only 16 bits dedicated to hosts.

For '''Class C''' networks, the range was therefore <tt>192.0.0.0</tt> to <tt>223.255.255.255</tt> with only eight bits dedicated to hosts.

==Special Classes==
Now '''Classes A''', '''B''', and '''C''' described all the normal addresses anyone would use, but there are two more classes.

A '''Class D''' network had a range of <tt>240.0.0.0</tt> to <tt>239.255.255.255</tt>. What makes this unusual is that there are '''zero''' bits dedicated to hosts. How can that be you ask? Well, all '''Class D''' addresses are used only for multicast. This makes sense, as one multicast address can be shared by hosts, and each expects to receive it.

The last network class is '''Class E''', which includes the rest of the address-space (<tt>240.0.0.0</tt> to <tt>255.255.255.255</tt>) and is reserved by the IANA to experimentation.

== See Also ==
[[CIDR]]
*RFC 791 ([[IP]])
*A lot of RFCs in between
*RFC 1166 (the last RFC to be used for network classes before [[CIDR]] came into effect)

{{stub}}

Netmask

2006-07-05T22:42:30Z

Osor:

#REDIRECT[[Subnet]]

CIDR

2006-07-05T22:32:55Z

Osor:

'''CIDR''' ('''C'''lassless '''I'''nter''' D'''omain '''R'''outing) is the strategy currently used for [[IP]] address assignment and routing. It is a replacement for the older and more rigid [[Network Class|classful networking]] scheme. The new method allows for flexible creation of network addresses through a variable number of bits unique to that network.

==See also==
*[[CIDR notation]]
*RFC 1517
*RFC 1518
*RFC 1519

{{stub}}

Talk:Subnet mask

2006-07-05T22:00:18Z

Osor:

Subnet

2006-07-05T21:57:31Z

Osor: /* Determining the network address */

All computers on the same network can directly send packets to eachother. When one sends a broadcast packet, all the rest get that packet (that is to say, they're all on the same "broadcast domain" -- aka "VLAN").

Routers connect networks together.

Typcially, a bunch of computers connected to eachother in one room form a network. Also typical is to assign them rfc1918 "reserved" addresses (look up that RFC for more info on those special IP addresses). Perhaps one computer on that network connects that network to the rest of the internet -- this computer is the so-called "gateway". It's performing routing, and is a router. Note, it's configured to not forward packets addressed to an rfc1918 address.

A '''subnet''' is a network, and is the set of all [[network interface]]s which have the same network address. You usually have one subnet per VLAN. If a machine on that subnet needs to talk to another machine on the subnet, it delivers the packet directly. Packets destined for other machines need to go through the gateway.

== Determining the network address ==

To determine the network address we use a subnet mask, or "netmask". This is a [[binary]] number that is used to "mask" an IP address into network and host address portions.

For example, an [[IPv4]] [[IP address]] and subnet mask are both 32 bits long. Take an address such as:

209.152.163.16

In binary this is:

11010001 10011000 10100011 00010000

The subnet mask is given as either a [[dotted decimal]] or in [[CIDR notation]] (using a bit count). For example, the Class B subnet mask is:

255.255.0.0

In binary this is

11111111 11111111 00000000 00000000

i.e. a string of 16 1's, followed by 0's. The [[CIDR]] representation is given as a forward-slash followed by the number of 1's:

/16

It is often appended to the end of the IP address.

209.152.163.16/16

The subnet mask is used to determine the network and host portions of an [[IP address]] in the following ways:

To determine the network address, apply a [[binary]] AND operation to the IP address and the subnet mask:

<pre>
11010001 10011000 10100011 00010000
11111111 11111111 00000000 00000000
-----------------------------------
11011001 10011000 00000000 00000000
</pre>

Converting this back to [[dotted decimal]] gives us a network address of:

209.152.0.0

All [[network interface]]s and computers that have this network address can be said to share the same subnet.

==More complex subnets==
Whilst this is a fairly trivial example, more complex subnets can be created by using a subnet mask that does not end on a margin between [[dotted decimal]] numbers.

A subnet mask of:

11111111 11111111 11100000 00000000

is

255.255.224.0

in [[dotted decimal]], or

/19

as a bit count. This type of subnetting is usually done by network administrators to create a number of subnetworks within a single class.

==See also==
*[[Networking basics]]

Talk:Subnet mask

2006-07-05T21:29:02Z

Osor:

I'm thinking the information on this page is already explained much better in [[Subnet]]. Would it be a good idea to get rid of this page? I'll give it a few days before taking action.
--[[User:Osor|Osor]] 17:29, July 5, 2006 (EDT)