Special:Investigate contains links to external tools, for deeper investigation into IP addresses, as depicted in T250290: CU 2.0: Show tool-links underneath IP addresses.

By default, Special:Investigate uses the links found in the checkuser-toollinks message.

These appear outdated, on closer inspection (substitute $1 with a valid IP):

• https://www.robtex.com/whois/$1.html and https://www.robtex.com/rbls/$1.html both redirect to the same URL
• http://www.dnsstuff.com/tools/tracert.ch?ip=$1 results in a 404 error
• https://www.dan.me.uk/torcheck?ip=$1 leads to a page stating that the tool is discontinued

We should ask check users what default links would be helpful as defaults.