Something that stuck with me from a previous job is the quote: “don’t underestimate things that have survived many attempts to kill them.”

Think: DNS, bash, C, TCP.

These things have survived this long for a reason. Find out the reason.

Another quote from the same job, upon receiving a page: “I don’t know what this service does, but I can tell you it isn’t doing it.”
@samwho a sense of humor always appreciated