My libreoffice calc is version 5.
Attached is a selection from the file from which I'd like to select the
duplicate hostnames and their IPv4 addresses.
The first two columns are the product of nMap searches on about 350 address
blocks. I've added a column which contains the results of nslookup on the
addresses in the second column. "92.242.140.21" resolves to barefruit
errorhandling, a catchall; one occurrence of 92.242.140.21 comes from a
single hostname which is probably duplicated elsewhere on the Internet. When
both duplicated hostnames are on the same /24 address block, it appears that
nslookup returns the first one's address only, masking the second one. The
nslookup result for alolika.su surprised me, as it is the correct IPv4
address for one instance of that hostname, leaving the second instance
completely hidden.
I've already removed all truly duplicated lines from the spreadsheet. The
second column therefore should contain no duplicated IPv4 addresses. Any
search for unique hostnames must therefore be applied only to the first
column.
