# Solved: my Subnet mask 255.255.255.255 is it possible ??



## lexicon (Sep 10, 2006)

hi i have a dialup connection.
after doing ipconfig i found the following output.

```
Windows IP Configuration

PPP adapter dialupinternet:
        Connection-specific DNS Suffix  . : 
        IP Address. . . . . . . . . . . . : 20x.7x.70.117
    Subnet Mask . . . . . . . . . . . : [B]255.255.255.255[/B]       
      Default Gateway . . . . . . . . . : 20x.7x.70.117
```
i'm a bit confused about my subnet mask how come it be 255.255.255.255 ?? :~
can anybody please make me clear about this matter

Thanks in advance.


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## gh0st3ncrypti0n (Nov 15, 2007)

The subnet mask can be modified to the users personal choice.
http://inside.drexel.edu/networking/subnet/winxp.asp

there's nothing wrong with 255.255.255.255, mine par example is 255.255.255.0 but I can change it to 255.255.255.255 if I'd want to.


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## calvin-c (May 17, 2006)

IIRC the subnet mask 255.255.255.255 means simply that there are no other systems on the same subnet as yours. I've never seen this myself but it sounds like it might be appropriate for a dialup connection.


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## lexicon (Sep 10, 2006)

any body have any idea ??? :~


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## calvin-c (May 17, 2006)

Well, I might-if you consider what I posted earlier to be an idea. Did you read it?


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## JohnWill (Oct 19, 2002)

Many dial-up and DSL connections get that subnet mask, perfectly normal.


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## lexicon (Sep 10, 2006)

Thanks Calvin-C Thanks John.
i hope my question was not silly, to annoy you .
btw 255.255.255.255 = which class subnet ??


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## JohnWill (Oct 19, 2002)

255.255.255.0 is a class C subnet, that would be a sub-C subnet.


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## lexicon (Sep 10, 2006)

255.0.0.0=Class A
255.255.0.0=Class B
255.255.255.0=Class C
255.255.255.255=Sub C subnet 
thanks
now can see the clear blue sky


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## JohnWill (Oct 19, 2002)

I see gray sky here, can you send some of the blue sky my way?


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## lexicon (Sep 10, 2006)

sorry john technology to transfer clouds have not been invented yet. AFAIK


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## lexicon (Sep 10, 2006)

oh sorry sorry you mean transfering blue sky .
you can download it from here ---> ftp bluesky.com
if you don't have an ftp account.
here's one bluesky http://www.bluesky.com/clipart/mainb2.gif


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## reezin14 (Oct 16, 2007)

That's pretty interesting I didn't know you could have a subnet like that.:up: Is this proprietary to dial-up ?


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## JohnWill (Oct 19, 2002)

I've seen that with some DSL modems too. Basically, all it's saying is there is a single node in the subnet.


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## O111111O (Aug 27, 2005)

^^^ What john said.

It's a /32. Quite normal for loopbacks and dead-end connections.

Dialup, some PPPOE, etc use this for the source IP address of your connection. The actually links et al are unnumbered or are in RFC1918 address space. Loopback connections have used this for > 10 years. 

It's becomming quite more commonplace as RIR's are forcing broadband carriers to use up 100% of their address space.


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## reezin14 (Oct 16, 2007)

This is good stuff to know,I don't hear about things like this at school.


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