Mark,
Thank you very much more this wonderful information. Question... If I have a class
"C" then anything I use behind the firewall can be assigned a 192 address? That way I
am not using all my IP address for internal networks. I have a DSL line at home and
getting ready to setup a hosting service. Small, just a few to start.
Thank you again.
Steven
*********** REPLY SEPARATOR ***********
On 2/23/2000 at 5:29 AM [EMAIL PROTECTED] wrote:
>IP Addressing
>IP address descriptions are found in RFC 1166, Internet Numbers. The
>Internet Network Information Center (InterNIC) maintains and distributes
>the RFC documents. The InterNIC also assigns IP addresses and network
>numbers to Internet Service Providers (ISPs), who in turn provide to their
>customers a range of addresses appropriate to the number of host devices
>on their network.
>The section that follows describe the various types of IP addresses, how
>addresses are given, and routing issues related to IP.
>IP addresses are written in dotted decimal notation consisting of four
>numbers separated by dots (periods). Each number, written in decimal,
>represents an 8-bit octet (sometimes informally referred to as a byte)
>giving each number a range of 0 through 255, inclusive. When strung
>together, the four octets for the 32-bit IP address.
>IP Address Notation
>
>32-Bit Value
>Dotted Decimal Notation
>01100100.01100100.01100100.00001010
>100.100.100.10
>11000011.00100000.00000100.11001000
>195.32.4.200
>The largest possible value of a field in dotted decimal notation is 255,
>which represents an octet where all the bits are 1s.
>IP Address Classes
>IP addresses are generally divided into different classes of addresses
>based on the number of hosts and subnetworks required supporting the
>hosts. As described in RFC 1166, IP addresses are 32-bit quantities
>divided into five classes. Each class has a different number of bits
>allocated to the network and host portions of the address.
>For example, 192.168.45.x describe a Class 'C' network with addresses
>ranging from 192.168.45.0 through 192.168.168.255.
>Class 'A' Addresses
>The class 'A' IP address format allocates the highest 8 bits to the
>network field and sets the highest-priority bit to 0(zero). The remaining
>24 bits form the host field. Only 126 class 'A' networks can exist (0 is
>reserved and 127 is used for loopback networks), but each class 'A'
>network can have almost 17 million hosts. No new class 'A' network can be
>assigned at this time.
>Class 'B' Addresses
>The class 'B' IP address format allocates the highest 16 bits to the
>network field and sets the two highest-order bits to 1 and 0, providing a
>range from 128 through 191, inclusive. The remaining 16 bits providing a
>range from 128 to 191, inclusive. The remaining 16 bits form the host
>field. More than 16,000 class 'B' networks can exist, and each class 'B'
>network can have up to 65,534 hosts.
>Class 'C' Addresses
>The class 'C' IP address format allocates the highest 24 bits to the
>network field and sets the three highest-order bits to 1,1, and 0,
>providing a range from 192 through 223, inclusive. The remaining 8 bits
>form the host field. More than two million class 'C' networks can exist,
>and each class 'C' network can have up to 254 hosts.
>Class 'D' Addresses
>The class 'D' IP address format was designed for multicast groups, as
>discussed in RFC 988. In class 'D' addresses, the 4 highest-order bits
>are set 1, 1, 1, and 0, providing a range from 224 through 239, inclusive.
>Class 'D' addresses is currently used primarily for the multicast backbone
>(MBONE) of the Internet. Many routers and firewalls do not support MBONE
>or multicast and therefore ignore class 'D' addresses.
>Class 'E' Addresses
>The Class 'E' IP address is reserved for future use. In Class 'E'
>addresses, the 4 highest-order bits are set to 1, 1, 1, and 1. Routers
>and Firewalls currently ignore class 'E' IP addresses.
>Reserved IP Addresses
>Some IP addresses are reserved for special uses and cannot be used for
>host addresses. The following table lists ranges of IP addresses and shows
>which addresses are reserved, which are available to be assigned and which
>are for broadcast.
>Class
>IP Address
>Status
>A
>0.0.0.0
>Reserved
>
>1.0.0.0 through 126.0.0.0
>Available
>
>127.0.0.0
>Loopback networks on the local host
>B
>128.0.0.0
>Reserved
>
>128.1.0.0 through 191.254.255.255
>Available
>
>191.255.0.0
>Reserved
>C
>192.0.0.0
>Reserved
>
>192.0.1.0 through 223.255.254.255
>Available
>
>223.255.255.0
>Reserved
>D
>224.0.0.0 through 239.255.255.255
>Multicast group addresses
>E
>240.0.0.0 through 255.255.255.254
>Reserved
>
>255.255.255.255
>Broadcast
>Private IP Networks
>RFC 1918 reserved three IP network addresses for private networks. The
>addresses 10.0.0.0/8, 192.168.0.0/16 and 172.16.0.0/20 can be used for
>anyone for setting up their own internal IP networks.
>
>
>
>
>Johann van Duyn <[EMAIL PROTECTED]>
>Sent by: [EMAIL PROTECTED]
>02/23/00 04:36 AM
>
>
> To: [EMAIL PROTECTED]
> cc:
> Subject: Private IP address ranges?
>
>
>
>
>Hi...
>
>I am planning on using NAT on my firewall, and need to know what IP
>address ranges are safe to use on my internal network, so as not to have
>addresses on my internal network that are the same as those of actual
>sites on the Internet. Could anyone please either tell me what the correct
>ranges would be for class A, B and C, or point me to a resource where I
>could find that info?
>
>Thanks
>
>Johann van Duyn
>
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