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No, the DNS service is run by Google out of their datacenters, they're just renting 8.8.8.0/24 and 8.8.4.0/24 off Level3 because they're memorable numbers. (It

by russss 17y ago

No, the DNS service is run by Google out of their datacenters, they're just renting 8.8.8.0/24 and 8.8.4.0/24 off Level3 because they're memorable numbers. (It's interesting because 4.2.2.[1-4] are run by Level3)

jganetsk 17y ago
My problem with posting online is I'm not a clear communicator. I understand that they are renting memorable IP addresses, and I understand that Google is running the DNS service out of the datacenter. I didn't say anything to the contrary. What I meant by Level3 hosting it is... Level3 is likely the single ISP in front of this service. I don't think Google can get away with multihoming this, other ISPs are just going to push 8.8.8.8 packets to Level3. I don't know how routing tables work, but I don't think they can reliably advertise ownership of the 8.8.8.* block considering it is wholly contained by another block.
- soundsop 17y ago
  Classless inter-domain routing (CIDR) was created exactly for the purpose of freeing up subnets: http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing.
  - jganetsk 17y ago
    Right, but can you have overlapping blocks? The wikipedia page says nothing about that. It talks about combining smaller blocks to make bigger ones (which is the interesting part). So, if I understand correctly, some routers will see Level3's 8...* advertisement and not Google's 8.8.8.*. They will route 8.8.8.8 to Level3, and that's OK, because Level3 is not going to just drop the packets on the floor. They will forward to Google. So this is why I said, in my original post, that Level3 is the home of Google's DNS service. If routers are respecting Google's own advertisement, it has to somehow be done with the permission of Level3.
- russss 17y ago
  No, that's not correct - you can see here that the route is being advertised through no less than 11 intermediate ISPs (and there will be more, that's just from one perspective on the internet): http://www.ris.ripe.net/cgi-bin/lg/index.cgi?rrc=RRC001&query=1&arg=8.8.8.0%2F24 http://www.ris.ripe.net/cgi-bin/lg/index.cgi?rrc=RRC001&... They're advertising 8.8.8.0/24, while Level3's route is 8.0.0.0/8 - the more specific route wins. Google is effectively a tier 1 ISP now, so buying transit off Level3 for those blocks would be a lot more costly than routing them themselves.
  - jganetsk 17y ago
    What do you mean that Google is a tier 1 ISP? Do they provide transit to anyone? Interestingly, if you can advertise a sub-block and override the bigger block's advertisement, what's stopping people from just stealing sub-blocks from ISPs?
    - blasdel 17y ago
      > what's stopping people from just stealing sub-blocks from ISPs? The thief has to either be upstream of your connection, or peered at an extremely high level with others trusting their BGP advertisements. There was a hilarious incident not that long ago where the Pakistanis accidentally blackholed YouTube's IP-block globally (instead of just within the country).

by russss 17y ago

jganetsk 17y ago

My problem with posting online is I'm not a clear communicator. I understand that they are renting memorable IP addresses, and I understand that Google is running the DNS service out of the datacenter. I didn't say anything to the contrary. What I meant by Level3 hosting it is... Level3 is likely the single ISP in front of this service. I don't think Google can get away with multihoming this, other ISPs are just going to push 8.8.8.8 packets to Level3. I don't know how routing tables work, but I don't think they can reliably advertise ownership of the 8.8.8.* block considering it is wholly contained by another block.

soundsop 17y ago
Classless inter-domain routing (CIDR) was created exactly for the purpose of freeing up subnets: http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing.
- jganetsk 17y ago
  Right, but can you have overlapping blocks? The wikipedia page says nothing about that. It talks about combining smaller blocks to make bigger ones (which is the interesting part). So, if I understand correctly, some routers will see Level3's 8...* advertisement and not Google's 8.8.8.*. They will route 8.8.8.8 to Level3, and that's OK, because Level3 is not going to just drop the packets on the floor. They will forward to Google. So this is why I said, in my original post, that Level3 is the home of Google's DNS service. If routers are respecting Google's own advertisement, it has to somehow be done with the permission of Level3.
russss 17y ago
No, that's not correct - you can see here that the route is being advertised through no less than 11 intermediate ISPs (and there will be more, that's just from one perspective on the internet): http://www.ris.ripe.net/cgi-bin/lg/index.cgi?rrc=RRC001&query=1&arg=8.8.8.0%2F24 http://www.ris.ripe.net/cgi-bin/lg/index.cgi?rrc=RRC001&... They're advertising 8.8.8.0/24, while Level3's route is 8.0.0.0/8 - the more specific route wins. Google is effectively a tier 1 ISP now, so buying transit off Level3 for those blocks would be a lot more costly than routing them themselves.
- jganetsk 17y ago
  What do you mean that Google is a tier 1 ISP? Do they provide transit to anyone? Interestingly, if you can advertise a sub-block and override the bigger block's advertisement, what's stopping people from just stealing sub-blocks from ISPs?
  - blasdel 17y ago
    > what's stopping people from just stealing sub-blocks from ISPs? The thief has to either be upstream of your connection, or peered at an extremely high level with others trusting their BGP advertisements. There was a hilarious incident not that long ago where the Pakistanis accidentally blackholed YouTube's IP-block globally (instead of just within the country).