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History of Networking: Policy with Joel Halpern

Policy at Internet scale is a little understood, and difficult (potentially impossible) to solve problem. Joel Halpern joins the History of Networking over at the Network Collective to talk about the history of policy in the Internet at large, and networked systems in general.

Enterprise versus Provider?

Two ideas that are widespread, and need to be addressed—

FANG (read this hyper/web/large scale network operators) have very specific needs; they run custom-built single-purpose software in a very big scale. So all the really want/need are dumb boxes and smart people. … Enterprise have another view, they want smart boxes run by dumb people.

First, there is no enterprise, there are no service providers. There are problems, and there are solutions.

When I was young (and even more foolish than I am now) I worked for a big vendor. When this big vendor split the enterprise and service provider teams, I thought this kindof made sense. After all, providers have completely different requirements, and should therefore run with completely different technologies, equipment, and software. When I thought of providers in those days, I thought of big transit network operators, like AT&T, and Verizon, and Orange, and Level3, and Worldcom, and… The world has changed since then, but our desire to split the world into two neat halves has not.

If you want to split the world into two halves, split it this way: There are companies who consider the network an asset, and companies that consider the network a Continue reading

The DNS Negative Cache

Considering the DNS query chain—

  • A host queries a local recursive server to find out about banana.example
  • The server queries the root server, then recursively the authoritative server, looking for this domain name
  • banana.example does not exist

There are two possible responses in this chain of queries, actually. .example might not exist at all. In this case, the root server will return a server not found error. On the other hand, .example might exist, but banana.example might not exist; in this case, the authoritative server is going to return an NXDOMAIN record indicating the subdomain does not exist.

Assume another hosts, a few moments later, also queries for banana.example. Should the recursive server request the same information all over again for this second query? It will unless it caches the failure of the first query—this is the negative cache. This negative cache reduces load on the overall system, but it can also be considered a bug.

Take, for instance, the case where you set up a new server, assign it banana.example, jump to a host and try to connect to the new server before the new DNS information has been propagated through the system. On Continue reading

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