IPv4 4th-octet question

[malania]

Hey guys,

 

I've been puzzled with a question since quite some time. Looks easy but google isn't helping me (or im not questioning it correctly >_< )

 

Anyway the question is regarding WAN IP - Suppose there are 2 wan IPs

 

1. 182.56.72.3

2. 182.56.72.2

 

Since the first 3 octet are same, does this mean that both IPs belong to same 'local' network? Does this mean that both the users coming to a site or anything are sitting next to each other? Are they on same WiFi?

 

[sc302 Veteran]

That means that those two IP's can belong to the same site or talk to each other without the need of a gateway.  A gateway, or router, is needed when communication has to go beyond the local network.  A gateway exists on the same network you are on and knows how to reach other networks via a (usually but not limited to a single) secondary interface on that device.

 

Being that they are right next to each other in that fashion it could mean a few things....they are part of a larger range, or are part of a smaller range.  or not part of a usable range at all.  Every network has a network identifier address and a broadcast address....if you break up the subnet into smaller portions those address are taken up by what you would normally consider usable addresses. 

 

Take a /30 subnet with that ip range.  182.56.72.2.  You will have 2 addresses that can be on that network that you can assign to a host (a host is a router, pc, server, any device you have physical control over and can touch).  Those two addresses are 182.56.72.1 and 182.56.72.2.  The network marker for that network is 182.56.72.0 and the broadcast address for that network is 182.56.72.3.  The next grouping in that /30 subnet is 182.56.72.4-182.56.72.7, .4 is your network marker and .7 is the broadcast address.  You can use a /29 to have a larger range of addressable hosts and so on.  You can use a subnet calculator to see how that works to make a little more sense of it.   It isn't just a WAN IP thing, it is a IP thing in general.

 

http://www.subnet-calculator.com/

 

[+BudMan MVC]

1 hour ago, malania said:

Does this mean that both the users coming to a site or anything are sitting next to each other? Are they on same WiFi?

Looks like sc302 got more into the nuts and bolts of subnetting vs answering what I take is your real question here.

 

Is that the actual IP?  If so seems to be some ISP in india?

 

inetnum:        182.56.0.0 - 182.59.255.255
netname:        MTNLISP
descr:          MTNL CAT B ISP
country:        IN

 

http://mtnldelhi.in/

 

While it could mean they are from the same company or the same network.  It could also mean they are from 2 different users of that ISP..  For example my public IP is 24.13.x.A, my neighbor or someone in the same service area might be 24.13.x.B -- doesn't mean we know each other or anything.  Just means we are users using the same ISP.

[malania]

well, @sc302 firstly thanks for the answer. The thing is, i got stuck in the subnet issue while googling hence your answer kinda went overboard >_<

 

@BudMan - yeah, well that sums it up. That isn't the actual IP though. I just made it up randomly. But more or less, that indeed what I was looking for.

 

The agenda is that my friend has an e-comm site and he noticed that a lot of tx started coming via similar public IPs. Only the last octet changed and that kinda looked fishy. Going by your logic - it seems someone or some peeps from same area are transacting a lot?

 

 

[+BudMan MVC]

yeah all that means is all the users are prob on the same ISP.

[malania]

On 10/21/2016 at 10:23 PM, BudMan said:

yeah all that means is all the users are prob on the same ISP.

Hey there, sorry for bringing the thread from the dead! If we continue with the same query, at what octet would you conveniently say that these 2 IPs are of different ISP?

1. 182.56.72.3

2. 182.56.72.2

 

Is it something like the IP above, if allotted to a specific ISP - is given the first 2 octets? or the first 3 maybe? wherein the last one could be anyone but part of the same ISP?

 

here's a case

 

1. 182.56.72.1

2. 182.56.73.1

 

What would you infer from this? do they belong to same ISP?

[goretsky Supervisor]

Hello,

 

You can always try running nslookup to determine the fully-qualified domain name returned for the IP address, if any.  

Another option would be to check the IP address block assignment with APNIC, ARIN, RIPE or other provider to see whom the block of IP addresses is registered.

 

Regards,

 

Aryeh Goretsky

[+BudMan MVC]

12 hours ago, malania said:

1. 182.56.72.1

2. 182.56.73.1

 

What would you infer from this? do they belong to same ISP?

Possible - as mentioned, possible you have to look it up... ISP normally have much larger blocks then single /24 So yeah your 72, 73 prob the same ISP.. As stated look it up with simple whois.

 

Your example

inetnum:        182.56.0.0 - 182.59.255.255
netname:        MTNL
descr:          Mahanagar Telephone Nigam Limited
country:        IN

 

That is a big chunk, all the same company!! 

 

As to your question which octet would it seem obvious they are different ISP.. Well if the 1st is different, 182, and say 185 I would assume they are different... But you really need to check to see who owns what, its possible that same ISP owns more than 1 /8, etc. Or chucks of /8 where the first octet is there for big chunks of the /8

 

NetRange:       24.0.0.0 - 24.15.255.255
CIDR:           24.0.0.0/12

And

NetRange:       24.16.0.0 - 24.23.255.255
CIDR:           24.16.0.0/13

 

Both owned by comcast... They also own the 73/8 etc. etc.

 

You really need to check to see...