net/http: `dns-should-not-resolve.golang` DNS record found in the `4.2.2.2` DNS server.

[jasonmoo]

Building go 1.7 with all.bash on osx/amd64, I noticed the following fail in the net/http package:

--- FAIL: TestTransportEventTraceRealDNS (0.06s)
    transport_test.go:3386: expected error during DNS lookup
FAIL

I dumped the httptrace used in the request that failed and found:

2016/08/15 22:23:02 DNSStart: {Host:dns-should-not-resolve.golang}
2016/08/15 22:23:02 DNSDone: {Addrs:[{IP:198.105.244.11 Zone:} {IP:198.105.254.11 Zone:}] Err:<nil> Coalesced:false}
2016/08/15 22:23:02 ConnectStart: tcp 198.105.244.11:80
2016/08/15 22:23:02 ConnectDone: tcp 198.105.244.11:80 <nil>

Seeing that the DNS was resolving I tested further with nslookup and discovered the DNS server I had been using (4.2.2.2) contained an entry.

jason@mba ~ : nslookup dns-should-not-resolve.golang
Server:     4.2.2.2
Address:    4.2.2.2#53

Non-authoritative answer:
Name:   dns-should-not-resolve.golang
Address: 198.105.244.11
Name:   dns-should-not-resolve.golang
Address: 198.105.254.11

Changing the DNS server to a different provider (8.8.8.8) showed no entry.

jason@mba ~ : nslookup dns-should-not-resolve.golang
Server:     8.8.8.8
Address:    8.8.8.8#53

** server can't find dns-should-not-resolve.golang: NXDOMAIN

This error has prevented my all.bash tests from passing. I'm not sure if there's a responsibility here to write tests that cannot be spoofed. What is the course to take?

[bradfitz]

Considering that the tests are for the continuous builders and developers, and most developers don't tolerate captive portals and lying DNS, I don't think we really need to do anything here.

[rakyll]

I don't think there is anything we can do better either.

The choice of the name is good enough -- non existing TLD, long and self documentary SLD. We unfortunately don't have control over every DNS server in the world to make this always pass. Renaming the name to something else doesn't protect us from experiencing the same issue due to the lying DNS servers.

[bradfitz]

I'll keep #16732 open at least to at least skip these types of tests during all.bash in short mode, unless you're on a builder.