Every record a domain publishes right now: A, AAAA, NS, MX, TXT, SOA and CAA in one place.
This is the plain view: everything the domain publishes, resolved now rather than from a cache we kept. It is the page to open when something is wrong and you do not yet know what.
Two things are worth a deliberate look. NS records tell you who is actually authoritative, which is often not who somebody believes is authoritative after a migration. And CAA names which certificate authorities may issue for the domain: publish none and any public CA may issue for you, which is a decision most people have not realised they are making.
Queries here use EDNS0 with a TCP fallback, so a large record set comes back complete. A truncated reply is how a lookup tool ends up showing you a domain's records with the important one missing.
Usually caching somewhere between you and the authority. This page resolves fresh each time, so a difference from another tool is often that the other tool cached.
No. This asks one resolver what the answer is now. A propagation check asks many resolvers around the world whether they agree yet, which is what you want during a migration.