Hello,
How to get the following Private IP range, whether I can only memorize them?
⦁ Class A: 10.0.0.0 – 10.255.255.255
⦁ Class B: 172.16.0.0 – 172.31.255.255
⦁ Class C: 192.168.0.0 – 192.168.255.255
Hello Chun
These are ranges of IP addresses that are defined by a standard and should simply be memorized. More information about the standard can be found at this NetworkLessons note about IPv4 Private IP address ranges.
I hope this has been helpful!
Laz
Oh I see, Thank your honest replay
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Hi Rene,
I tried to ping 127.0.0.1 127.0.0.2 127.0.0.3 1270.0.254, I got loopback message. So, am I right to infer that address range from 127.0.0.1 to 127.255.255.254 are addresses reserved for loopback and 127.0.0.0 is the network address and 127.255.255.255 is for network broadcast ?
If I am wrong, please correct me.
Thanks and Best regards,
Charles
Hello Charles
The 127.0.0.0/8 address range is called the Internal host loopback address range. Addresses of this form are used to refer to the host itself. If you were to ping any of these addresses on any network device, you should get a response. This is because these addresses refer to the local host. This address range is defined in full in section 3.2.1.3.g of RFC 1122.
In practice, any ping to an IP address of 127.0.0.1 all the way up to 127.255.255.254 will have a response from the local host assuming that the IP protocol stack (the interface itself that is) is up and running. Now theoretically, the 127.0.0.0 and 127.255.255.255 addresses are reserved for network and broadcast respectively, however, in practice, these have no meaning in the context of the local loopback. Indeed I tried pinging 127.0.0.0 on my PC and I got a general failure message. Similarly, I got no response from 127.255.255.255. So these addresses in reality are meaningless in this context.
I hope this has been helpful!
Laz
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Hi Rene,
Thank you for possibility of discussion in connection to lesson material. Personally I am obtaining a big benefit from this blog. Your replay is comprehensive to question. Thank you.
Actually, I think about loopack addresses and realize that there is a wastage , is not? So many addresses dedicated to be loopback in its purpose in the situation when we have shortage of iPv4 addresses? I realize that dedicated loopback range would be standardized in the situation when shortage was not visible yet.
Hello Rafal
Yes, I agree with you! Setting aside the range of 127.0.0.0/8 means that you’re setting aside over 16 million addresses just for the host loopback address!! Remember that the IPv4 protocol was designed primarily in the early 1980s, so there was no way for engineers to foresee address exhaustion as a problem almost forty years later! So they set aside way too many addresses for loopback. There were other seemingly wasteful allocations as well, including the 240.0.0.0/4 which has been set aside for experimental use/future use.
They could change this definition to free up addresses, but I think they decided against it since IPv6 had already been designed in the late 1990s, and was expected to be rolled out sooner.
IPv6 has taken this wastage into account, and even though there are many more available addresses, the loopback address in IPv6 is a single address:
0:0:0:0:0:0:0:1/128 or ::1/128
This IPv6 loopback is defined in RFC 4291.
I hope this has been helpful!
Laz
Can I have explanation in subnetting . I have seen the difference of playing octets in class a b c. I observe that for class c only fourth octet is played while doing subnetting . I can see it has got host bits only in fourth octet. But when it comes to Class b they are host bits in both third and fourth octet. But only third octet is played in class b subnetting. Similarly in class a only second octet is played but they are host bits in both second, third and fourth
Hello Pavan
Take a look at this NetworkLessons course on subnetting.
There you will find all of the information you need to successfully understand the process. I suggest you begin with the following introduction, and as you go along, let us know of any additional questions or clarifications.
I hope this has been helpful!
Laz