network configuration problem in ubuntu 9.10

Tony Arnold tony.arnold at manchester.ac.uk
Sun Mar 14 09:44:05 UTC 2010


Nils,

Nils Kassube wrote:

>> True. As your IP address is a class A address, I would expect the
>> netmask to be 255.0.0.0
> 
> If you try "whois 58.196.140.8" you can see that the address range of 
> that network is 58.196.0.0 - 58.197.255.255, i.e. it is a /15 network. 

I missed that little nugget!

> The historical network class A is more or less obsolete [1].

Hmm, I should stop living in the past!

> For a /15 
> network the netmask would be 255.254.0.0 _but_ we don't know anything 
> about the internal subnet, which makes the netmask a wild guess on our 
> side. If the OP got a netmask of 255.255.255.0 from the network admin, 
> it is sure possible. But, like Tom H wrote, the gateway should be within 
> the address range of the netmask. We only know that one of the three 
> (address, gateway or netmask) is wrong.

I agree. And if you do a whois for the gateway address, you get a more
of the story (possibly)! The gateway address 58.194.128.1 is part of the
range 58.194.128.0 - 58.194.143.255 which is a /20 address (I think) and
belongs to Ningxia University in China. Where as the IP address belongs
to CERNET (China Education and Research Network).

So, yes, the values given are inconsistent and one or more of them is
wrong. The OP should consult their local network support team!

Regards,
Tony.
-- 
Tony Arnold,                        Tel: +44 (0) 161 275 6093
Head of IT Security,                Fax: +44 (0) 870 136 1004
University of Manchester,           Mob: +44 (0) 773 330 0039
Manchester M13 9PL.                 Email: tony.arnold at manchester.ac.uk




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