dnsmap is a fantastic tool to find subdomains within the domain you are looking for. It's a great way to see whether other sites are publicly available (internally and/or externally) that may or may not be known. This allows you to potentially find and exploit a subdomain that may not be controlled or administered correctly. You can provide your own word list to look up against the subdomains, or you can use the built-in one. Some organizations offload some subdomains to third parties, so you need to be cautious how you use this information. The scope of work may only cover the company you are hired for; and therefore, you may not be looked upon so kindly by the other organization if you are trying to actively exploit it. This should be worked out in the stakeholders meeting, but sometimes things do slip through the floor. The following is a screenshot...
United States
United Kingdom
India
Germany
France
Canada
Russia
Spain
Brazil
Australia
Argentina
Austria
Belgium
Bulgaria
Chile
Colombia
Cyprus
Czechia
Denmark
Ecuador
Egypt
Estonia
Finland
Greece
Hungary
Indonesia
Ireland
Italy
Japan
Latvia
Lithuania
Luxembourg
Malaysia
Malta
Mexico
Netherlands
New Zealand
Norway
Philippines
Poland
Portugal
Romania
Singapore
Slovakia
Slovenia
South Africa
South Korea
Sweden
Switzerland
Taiwan
Thailand
Turkey
Ukraine