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I am a bit confused.

I would like to know since when a current ASN (and its corresponding prefixes) have been in place.

When I look at the example at team-cymru (http://www.team-cymru.com/IP-ASN-mapping.html) I see:

$ whois -h whois.cymru.com " -v 216.90.108.31 2005-12-25 13:23:01 GMT"

AS      | IP               | BGP Prefix          | CC | Registry | Allocated  | Info                    | AS Name
23028   | 216.90.108.31    | 216.90.108.0/24     | US | arin     | 1998-09-25 | 2005-12-25 13:23:01 GMT | TEAMCYMRU - SAUNET
You may also query for some basic AS information directly:

$ whois -h whois.cymru.com " -v AS23028"

AS      | CC | Registry | Allocated  | AS Name
23028   | US | arin     | 2002-01-04 | TEAMCYMRU - SAUNET

So, the ASN 23028 and it BGP prefix 216.90.108.0/24 have been allocated in 1998 or in 2002?

Thanks!

ℕʘʘḆḽḘ
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1 Answers1

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The netblock the IP address 216.90.108.31 is in was originally allocated on 1998-09-24.

The autonomous system number 23028 was registered on 2002-01-04.

Their registration dates have no relation to each other, nor is there any reason for them to. IP netblocks and AS numbers are independent. Routes can change at any time. So can ASNs.

Michael Hampton
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  • thanks Michael, but I thought that with one AS came a CIDR block, hence a range of IP addresses? isnt it the case? – ℕʘʘḆḽḘ Aug 04 '18 at 12:58
  • @ℕʘʘḆḽḘ No, you don't get IP blocks with an AS, or vice versa. They are completely independent. You might happen to register them on the same day, or get them both from ARIN, but they are separate processes and handled entirely separately. – Michael Hampton Aug 04 '18 at 13:00
  • thanks I didnt know that. What I am trying to do is the following. I have a bunch of IP addresses collected over time (say the last few years) and I am trying to map them to their corresponding AS number. What would you recommend here? Assume I have a lot of addresses... Thank you again! – ℕʘʘḆḽḘ Aug 04 '18 at 13:04
  • @ℕʘʘḆḽḘ You can just run whois to see the _current_ AS. But that won't necesasrily tell you what AS the address was routed to years ago. – Michael Hampton Aug 04 '18 at 13:15
  • yes, that is why I was planning to use the allocation dates. But what you are suggesting is that the two (AS and IP allocation are different). Lets say I start with a given AS, I can retrieve the allocation date. Is there a way to pull the allocation dates for its corresponding IP range then? this is the missing point here. – ℕʘʘḆḽḘ Aug 04 '18 at 13:16
  • @ℕʘʘḆḽḘ Again, you can just run whois to find out when IP addresses were assigned. But be sure to look at the parent allocations, too. Which date or entity you want depends on what you are doing. – Michael Hampton Aug 04 '18 at 13:18
  • thank you. just a noob question: running a whois on the AS number you mean? Can I possibly pull information for thousands of AS without abusing the servers? – ℕʘʘḆḽḘ Aug 04 '18 at 13:19
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    @ℕʘʘḆḽḘ I think Team Cymru has a downloadable list that they try to keep updated. Poke around their website. – Michael Hampton Aug 04 '18 at 13:20
  • if you could provide me with the link that would be amazing. I have looked on their website without success.... sorry for my noobness here. in any case thanks again for all these clarifications – ℕʘʘḆḽḘ Aug 04 '18 at 13:21