DNS queries of does-not-exist.example.com and example.invalid

This bug was originally filed in Launchpad as [LP: #1658734](https://bugs.launchpad.net/cloud-init/+bug/1658734)

Launchpad details

affected_projects = ['cloud-init (CentOS)']

assignee = None

assignee_name = None

date_closed = None

date_created = 2017-01-23T16:56:19.002698+00:00

date_fix_committed = None

date_fix_released = None

id = 1658734

importance = wishlist

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1658734

milestone = None

owner = ajorgens

owner_name = Andrew Jorgensen

private = False

status = triaged

submitter = ajorgens

submitter_name = Andrew Jorgensen

tags = []

duplicates = []

_Launchpad user **Andrew Jorgensen(ajorgens)** wrote on 2017-01-23T16:56:19.002698+00:00_

cloud-init makes several DNS queries for does-not-exist.example.com and example.invalid (and also some random names). https://git.launchpad.net/cloud-init/tree/cloudinit/util.py#n1100

We understand that it does this to detect the kind of DNS redirection that's done an many universities, some ISPs, and services like OpenDNS (when used for filtering or typo correction).

However, it can be problematic in an environment where an intrusion detection system might flag these queries as potentially malicious, and in a system where DNS redirection is not used it unnecessarily increases boot time.

It looks like the feature was written to make it possible to disable it or provide specific redirection IPs, but that it never gained a config option to control it.