A Trivial Caching DNS
A normal Red Hat 7 installation includes a caching DNS implementation. Depending on the exact install method, and post-install configuration activities, this installation-default setup may have a flaw, making it excessively slow on any reverse DNS lookup (more on reverse DNS later in the Configuring DNS Server Master Zones section of this chapter). This problem can be verified by using telnet to access the newly installed machine. If this flaw exists, telnet will typically take 30 seconds or more to ask for the username and may time out entirely. Note that it's possible for slow telnet to be caused by flawed forward (name to number) resolution, although this is less common.
The following code contains the installation-default ...
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