The remote Debian host is missing a security-related update.
Tony Finch and Marco Davids reported an assertion failure in BIND, a DNS server implementation, which causes the server process to terminate. This denial-of-service vulnerability is related to a defect in the processing of responses with DNAME records from authoritative servers and primarily affects recursive resolvers.
Upgrade the bind9 packages. For the stable distribution (jessie), this problem has been fixed in version 1:9.9.5.dfsg-9+deb8u8.