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
Great Britain
India
Germany
France
Canada
Russia
Spain
Brazil
Australia
Singapore
Hungary
Philippines
Mexico
Thailand
Ukraine
Luxembourg
Estonia
Lithuania
Norway
Chile
South Korea
Ecuador
Colombia
Taiwan
Switzerland
Indonesia
Cyprus
Denmark
Finland
Poland
Malta
Czechia
New Zealand
Austria
Turkey
Sweden
Italy
Egypt
Belgium
Portugal
Slovenia
Ireland
Romania
Greece
Argentina
Malaysia
South Africa
Netherlands
Bulgaria
Latvia
Japan
Slovakia