Comment 83 for bug 94940

Thank you for a detailed and competent answer. This clarifies the issue. Now it makes sense why this cannot and should not be fixed in Ubuntu.

To summarize: If you experience lookup delays, change your /etc/nsswitch.conf to this:

$ cat /etc/nsswitch.conf

# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.

passwd: compat
group: compat
shadow: compat

# https://bugs.launchpad.net/ubuntu/+source/nss-mdns/+bug/94940

# Original, delayed lookup on improperly configured internal networks:
#hosts: files mdns4_minimal [NOTFOUND=return] dns

# Use this if you're not on a local network with Microsoft services or if you don't need on them:
#hosts: files dns

# Delays looking up hosts on your internal network, but you *will* get the best of both worlds;
# multicast DNS resolution *and* resolution of your incorrectly-named internal network:
hosts: files mdns4_minimal dns

networks: files

protocols: db files
services: db files
ethers: db files
rpc: db files

netgroup: nis