I am new to Pi-Hole, and had a search but can't see anything related to this.
In the "Query Log", external domains seem to be concatenated with the local LAN. I'm not sure why this is happening?
In the UI I tried to leave the "Pi-hole domain name" field blank and save it, however its keeps erroring and fails to save due to the field being blank.
Many thanks for the reply. I have attached a screenshot from the query log which shows the same host querying domains concatenated, with various extensions; including my local domain (*.lan).
Most networking utilities and applications will try to resolve a given hostname by appending the local search domain suffix (that's the point of having that, after all), e.g. nslookup does so while dig doesn't by default (you can enforce it using dig +search).
The situation is less consistent with regards to expanding fully qualified domain names (like www.wikipedia.org) by a search suffix, e.g. Windows nslookup will do so by default, while Linux versions may or may not (as controlled by the ndots option, e.g. see man resolv.conf).
So if you e.g. run nslookup from a Windows command prompt, you'll see two sets of DNS queries arriving in Pi-hole's Query Log, one with the suffix appended and one without.