A Short History of Chaosnet

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2022-01-13 22:30:05

The output contains both a section describing the “question” you asked (“What is the IP address of google.com?”) and a section describing the answer you received. In the answer section, we see that dig found a single record with what looks to be five fields. The record’s type is indicated by the A in the fourth field from the left—this is an “address” record. To the right of the A, in the fifth field, we can see that the IP address for google.com is 216.58.192.206. The 194 value in the second field specifies how long in seconds this particular record can be cached.

What does the IN field tell us? For an embarrassingly long time, I thought IN functioned as a preposition, so that every DNS record was saying something like “google.com is in A and has IP address 216.58.192.206.” It turns out that IN actually stands for “internet.” The IN part of a DNS record tells us the record’s class.

Why might a DNS record have a class other than “internet”? What would that even mean? How do you search for a host that isn’t on the internet? It would seem that IN is the only value that could possibly make sense here. Indeed, when you try to ask for the address of google.com while specifying that you expect a record with a class other than IN, the DNS server you are asking will probably complain. In the below, when we try to ask for the IP address of google.com using the HS class, the name server at 8.8.8.8 (Google Public DNS) returns a status of SERVFAIL: