Common operational misconceptions

Dan White dwhite at
Wed Feb 15 21:52:01 UTC 2012

On 02/15/12 14:47 -0600, John Kristoff wrote:
>Hi friends,
>As some of you may know, I occasionally teach networking to college
>students and I frequently encounter misconceptions about some aspect
>of networking that can take a fair amount of effort to correct.
>For instance, a topic that has come up on this list before is how the
>inappropriate use of classful terminology is rampant among students,
>books and often other teachers.  Furthermore, the terminology isn't even
>always used correctly in the original context of classful addressing.
>I have a handful of common misconceptions that I'd put on a top 10 list,
>but I'd like to solicit from this community what it considers to be the
>most annoying and common operational misconceptions future operators
>often come at you with.
>I'd prefer replies off-list and can summarize back to the list if
>there is interest.

I almost always see someone fill in the 'default gateway' field when
they're configuring a temporary address on their computer to communicate
with a device on the local network.

On the topic of VLANs, it's common to think of 'trunking' and something
that happens between switches. It's hard to get someone to ponder the
fact that trunking isn't an all or nothing concept, and that a server can
be configured to speak vlan.

Confusing ftp, sftp, ftps. Or telnet, telnets, ssh.

Packet loss at hop X in traceroute/mtr does not necessarily point to a
problem at hop X.

BGP does not magically load balance your ingress and egress traffic.

Just because it's down for you, doesn't mean it's down for everyone.

Dan White

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