This is a very simple formula you can always use to calculate subnets:
first subnet address N = 256 - X
second subnet = (N)2
third subnet = (N)3
and so on …
Here X is the octet in which the bits are borrowed for the hosts.
Subnet mask: 255.255.255.248
here 248 is the octet from which bits are borrowed for hosts. In this example 3 bits are borrowed and the total number of hosts possible for this subnet mask per subnet is:
(2 ^ 3) - 2 = 7 Hosts
because 256 - 248 = 8
so for your first question after your correction the subnet addresses will increment in multiples of "8".
for your second question, the answers from the website you are talking about jut cant be correct. You may need to recheck or it’s an error by the author.
the third question ....
IP 127.0.0.1 is like ... your home address ...
if you sent a mail to your home address and if you received it too then you can be sure that the postal service is working fine for your residence address ...
only an analogy ... I’m sure your postal service need not be reinstalled like a defective TCP/IP stack
127.0.0.1 is reserved as a loopback address or in other words TCP/IP when installed by default assigns itself the 127.0.0.1 IP for loopback testing purpose .... and if you are able to ping this IP then that would mean that your TCP/IP stack is working properly, application thru physical layer and there is no problem with it.
try using this command and figure out who is this "localhost" :wink: :
hope this helps ...
Re: undeliverable email
15 years 5 months ago #2396
i jus checked the answers are the ip addresses with the following numbers for its 1st octet.....its 124....
and 186...but i thawt it was right...coz the mask is 224
and that gives a subnet of 256-224=32
so subnets of 0,32,64,96.....
the ip addresses with these as their 3rd octet shuld be subnets and the rest could be valid hosts right?hmmm
its okye i have plenty of qns today as well...when u configure for PPP....and u type username RouterB passwrd xxx
the username n passwrd should be of the other router right?
and we type this in router A's config? what happens actually?
thx alot indebluez:)
Re: undeliverable email
15 years 5 months ago #2397
The localhost question as been answered pretty well. But the reason you cannot use 127.0.0.0 is because this the network address (the wire). 127.0.0.1 is the normal address for localhost and is listed this way in your hosts file.
But in actuality, any address starting with 127, except 127.0.0.0 (network) and 127.255.255.255(broadcast) should also work as your loopback address.
If you ping 127.150.20.5, for instance, you should still get a response. You won't get one for 127.0.0.0 and 127.255.255.255.
As to your subnetting question the author is correct for a subnet mask of 255.255.224.0. 32 is what some would refer to as your magic number therefore 32 and 160 are valid subnet address and not host ip addresses.
The last 5 bits of the third octet and all eight bits in the last octet are host bits and you have to have at least one of them as a binary 1. The other three answers meet the criterial of having at least one binary 1 in the last 13 bits.
As to your PPP question the most common mistake is to think of the password as already being used somewhere else i.e. the enable password. This is a totally new password and must be the same on both routers. Otherwise yes to your question as you are making a user list to allow the other router to establish a PPP link with you and the other router has to do the same.
By the way you did not ask about authentication but I am assuming you are configuring this as well and using either PAP or CHAP. Otherwise you do not need a user list.