86: Take Quite a Long Time to Fail

Here’s a chunk of the networking book.

Standard netstat attempts to show hostnames instead of IP addresses. This means your server performs a reverse DNS lookup on every IP address it exchanges traffic with. On a busy server, this might mean hundreds or thousands of lookups. The output pauses for each lookup. Many hosts have no reverse DNS, so these lookups can take quite a long time before they fail.

Service names also appear with a human-friendly name rather than a port number whenever possibl...