At a previous job, we had a customer who suddenly couldn’t send us email anymore. When their IT sent us the server logs to “prove” it’s our fault, we saw that the one letter in the cached MX record was wrong. This was puzzling, until I looked at the ASCII table to verify that the difference was exactly one bit.
We never found out where in the name resolution process the bit got flipped. The problem healed itself a few days later when the DNS cache expired, so it wasn’t worth further investigation.
That really gave me pause how often random bits are wrong in other data.
At a previous job, we had a customer who suddenly couldn’t send us email anymore. When their IT sent us the server logs to “prove” it’s our fault, we saw that the one letter in the cached MX record was wrong. This was puzzling, until I looked at the ASCII table to verify that the difference was exactly one bit.
We never found out where in the name resolution process the bit got flipped. The problem healed itself a few days later when the DNS cache expired, so it wasn’t worth further investigation.
That really gave me pause how often random bits are wrong in other data.