In the early 90s I worked for a place whose phone number was apt to be published in a news story about the Internet. So people who wondered what it was, and how to get on it, would call that number and reach us.
We had 2-3 part-time employees answering phones, voicemail and email. As you can imagine, we were effectively DDOS'd and we knew it, every time a national news story hit the presses.
Our #1 response to individual callers was to send them a list of dial-up ISPs. This list could be had on anonymous FTP, but since our callers were not yet online, we printed out the list, on demand, and popped it in the outgoing postal mail, each and every time. That printer was the most unreliable device in the office.
Meanwhile, in the same office, we ran an ISP which offered dialup service to a few thousand users. The authentication server needed to read /etc/passwd sequentially, each time a modem answered. The usernames were often found at the bottom of the file. So at peak hours, our authentication server began timing out, backlogged with the requests and the ever-growing user roster.
So I took the server code and introduced a RAM cache. It read /etc/passwd and held it in memory until the file was modified on disk. We swapped in the new code and it immediately smoothed everything out again. The operators all breathed a sigh of relief.