dnsdump
DNS isn’t only used to resolve hostnames to IP addresses. It also provides information about mail servers, name servers, aliases, etc. for a domain. Each of these corresponds to a specific type of DNS record. If you want all (or at least some of) the resource records for a domain, you can make a DNS “ANY” query. According to RFC 8482 however, DNS servers aren’t required to respond with the desired records.
dnsdump
fetches a bunch of DNS records for a domain without using the “ANY” query. It sends an asynchronous request for each record type and, once every request has completed, spits out the results in a legible format.