An authoritative DNS server answers requests from resolvers, using information about the domain names it is authoritative for. You can provide DNS services on the Internet by installing this software on a server and giving it information about your domain names. The BIND 9 documentation includes a description of the Primary/Secondary/Stealth Secondary roles for authoritative servers.
RRL
Response Rate Limiting (RRL) is an enhancement to named to reduce the problem of “amplification attacks” by rate-limiting DNS responses. This feature is on by default because it has proven to be so effective; it’s now even more effective with DNS Cookies, which focus rate-limiting on unknown clients. DNS cookies, per RFC 7873, are exchanged between client and server to provide IP address identity, helping to prevent attacks using forged IP addresses. Servers enforcing cookies are less susceptible to being used as an effective attack vector for DNS DDOS attacks.
Minimal ANY Responses
Queries for ANY records are a possible abuse mechanism because they typically extract a response much larger than the query. The minimal-any option reduces the size of answers to UDP queries for type ANY by implementing one of the strategies in “draft-ietf-dnsop-refuse-any”: returning a single arbitrarily-selected RRset that matches the query name rather than returning all of the matching RRsets.
DLZ
Dynamically Loadable Zones (DLZ) enable BIND 9 to retrieve zone data directly from an external database. Not recommended for high-query rate authoritative environments.
Minimum Re-load Time
Update your BIND 9 server zone files with the remote name daemon control (rndc) utility, without restarting BIND 9. For those times when you do have to restart, the ‘map’ zone file format can dramatically speed up reloading a large zone file into BIND 9, such as on restart.
HSM Support
HSMs are used to store key material outside of BIND 9 for security reasons. BIND 9 supports the use of Hardware Security Modules through the OpenSSL PKCS#11 provider, which ISC has helped to improve.
DNSSEC with Inline Signing
BIND 9 fully supports DNSSEC and has a mature, full-featured, easy-to-use implementation. Once you have initially signed your zones, BIND 9 can automatically re-sign dynamically updated records with inline signing. BIND’s Key and Signing Policy utility will help you maintain your DNSSEC implementation, periodically updating keys and signatures according to the policy you establish.
Catalog Zones
Catalog zones facilitate the provisioning of zone information across a nameserver constellation. Catalog zones are particularly useful when there is a large number of secondary servers. This feature will automatically propagate new zones added to the primary to the secondary servers, or remove zones deleted from the primary, eliminating the need for separate scripts to do this.
dnstap
Dnstap is a fast, flexible method for capturing and logging DNS traffic, developed by Robert Edmonds at Farsight Security, Inc. Dnstap is supported by several open-source DNS servers, including BIND. Using dnstap enables capturing both query and response logs, with a reduced impact on the overall throughput of the BIND server than native BIND logging. Messages may be logged to a file or to a UNIX socket. Support for log-file rotation will depend on which option you choose. A utility ‘dnstap-read’ has been added to allow dnstap data to be presented in a human-readable format.
Scaleable Primary-Secondary Hierarchy
A DNS authoritative system is composed of a primary with one or more secondary servers. Zone files are established and updated on a primary server. Secondaries maintain copies of the zone files and answer queries. This configuration allows scaling the answer capacity by adding more secondaries, while zone information is maintained in only one place. The primary signals that updated information is available with a NOTIFY message to the secondaries, and the secondaries then initiate a zone transfer from the primary. BIND 9 fully supports both the AXFR (complete transfer) and IXFR (incremental transfer) methods, using the standard TSIG security mechanism between servers. There are a number of configuration options for controlling the zone updating process.
