DNS Inspection tools

The DNS Operations, Analysis, and Research Center (DNS-OARC) brings together key operators, implementors, and researchers on a trusted platform so they can coordinate responses to attacks and other concerns, share information and learn together.

Further reading on DNS

FQDN Uppercase – Lowercase weirdness

The DNS is not case sensitive, but it’s generally expected that servers will respect the case that was observed in the client query.
Some clients take advantage of this to add extra entropy to the query to help mitigate packet spoofing attacks.
Use of Bit 0x20 in DNS Labels to Improve Transaction Identity: draft-vixie-dnsext-dns0x20-00.txt



for my German friends:

Windows DNS Server

DNS – Performance

Fast Web Performance Starts with DNS

IETF – Domain Name System (DNS) Parameters


  • RFC5395 Domain Name System (DNS) IANA Considerations
  • RFC3597 Handling of Unknown DNS Resource Record (RR) Types

IANA – Protocol Registries

Domain Name System (DNS) Parameters

Domain Name System (DNS) Parameters
AFSDB RR Subtype RFC 6895, RFC 1035
Registry closed per
Child Synchronization (CSYNC) Flags RFC 7477
Standards Action
DHCID RR Identifier Type Codes RFC 4701
Standards Action (Expert: Olafur Gudmundsson)
0: Standards Action. 1-127: IETF Review. 128-253: IETF Review. 256-32767: IETF Review. 32768-57343: Specification Required. 57344-65279: Specification Required. 65280-65534: Reserved for Private Use. 65535: Standards Action.
DNS EDNS0 Option Codes (OPT) RFC 6891
Expert Review (Expert: Olafur Gudmundsson)
DNS Header Flags RFC 6895, RFC 1035
Standards Action
DNS KEY RR Protocol Octet Values RFC 4034, RFC 2535
DNS Label Types RFC 6891
Standards Action
DNS OpCodes RFC 6895, RFC 1035
Standards Action
DNS RCODEs RFC 6895, RFC 1035
IETF Review
DNSKEY RR Flags RFC 3755, RFC 4034
Standards Action
EDNS Header Flags (16 bits) RFC 6891
Standards Action
EDNS version Number (8 bits) RFC 6891
Standards Action
Resource Record (RR) TYPEs RFC 6895, RFC 1035
0: RRTYPE zero is used as a special indicator for the SIG RR , and in other circumstances and must never be allocated for ordinary use.. 1-127: DNS RRTYPE Allocation Policy. 128-255: DNS RRTYPE Allocation Policy. 256-61439: DNS RRTYPE Allocation Policy. 61440-65279: IETF Review. 65280-65534: Reserved for Private Use. 65535: Reserved (Standards Action).
SSHFP RR types for fingerprint types RFC 4255
IETF consensus
SSHFP RR Types for public key algorithms RFC 4255
IETF consensus

IANA – Domain Name System (DNS) Parameters

Resource Record (RR) TYPEs

Available Formats

Decimal Hex Registration Procedures Note
0 0x0000 RRTYPE zero is used as a special indicator for the SIG RR [RFC2931], [RFC4034] and in other circumstances and must never be allocated for ordinary use.
1-127 0x0000-0x007F DNS RRTYPE Allocation Policy data TYPEs
128-255 0x0080-0x00FF DNS RRTYPE Allocation Policy Q TYPEs, Meta TYPEs
256-61439 0x0100-0xEFFF DNS RRTYPE Allocation Policy data RRTYPEs
61440-65279 0xF000-0xFEFF IETF Review
65280-65534 0xFF00-0xFFFE Reserved for Private Use
65535 0xFFFF Reserved (Standards Action)
TYPE Value Meaning Reference Template Registration Date
A 1 a host address [RFC1035]
NS 2 an authoritative name server [RFC1035]
MD 3 a mail destination (OBSOLETE – use MX) [RFC1035]
MF 4 a mail forwarder (OBSOLETE – use MX) [RFC1035]
CNAME 5 the canonical name for an alias [RFC1035]
SOA 6 marks the start of a zone of authority [RFC1035]
MB 7 a mailbox domain name (EXPERIMENTAL) [RFC1035]
MG 8 a mail group member (EXPERIMENTAL) [RFC1035]
MR 9 a mail rename domain name (EXPERIMENTAL) [RFC1035]
NULL 10 a null RR (EXPERIMENTAL) [RFC1035]
WKS 11 a well known service description [RFC1035]
PTR 12 a domain name pointer [RFC1035]
HINFO 13 host information [RFC1035]
MINFO 14 mailbox or mail list information [RFC1035]
MX 15 mail exchange [RFC1035]
TXT 16 text strings [RFC1035]
RP 17 for Responsible Person [RFC1183]
AFSDB 18 for AFS Data Base location [RFC1183][RFC5864]
X25 19 for X.25 PSDN address [RFC1183]
ISDN 20 for ISDN address [RFC1183]
RT 21 for Route Through [RFC1183]
NSAP 22 for NSAP address, NSAP style A record [RFC1706]
NSAP-PTR 23 for domain name pointer, NSAP style [RFC1348][RFC1637][RFC1706]
SIG 24 for security signature [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2931][RFC3110][RFC3008]
KEY 25 for security key [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2539][RFC3008][RFC3110]
PX 26 X.400 mail mapping information [RFC2163]
GPOS 27 Geographical Position [RFC1712]
AAAA 28 IP6 Address [RFC3596]
LOC 29 Location Information [RFC1876]
NXT 30 Next Domain (OBSOLETE) [RFC3755][RFC2535]
EID 31 Endpoint Identifier [Michael_Patton][] 1995-06
NIMLOC 32 Nimrod Locator [1][Michael_Patton][] 1995-06
SRV 33 Server Selection [1][RFC2782]
ATMA 34 ATM Address [ ATM Forum Technical Committee, “ATM Name System, V2.0”, Doc ID: AF-DANS-0152.000, July 2000. Available from and held in escrow by IANA.]
NAPTR 35 Naming Authority Pointer [RFC2915][RFC2168][RFC3403]
KX 36 Key Exchanger [RFC2230]
CERT 37 CERT [RFC4398]
A6 38 A6 (OBSOLETE – use AAAA) [RFC3226][RFC2874][RFC6563]
SINK 40 SINK [Donald_E_Eastlake][] 1997-11
OPT 41 OPT [RFC6891][RFC3225]
APL 42 APL [RFC3123]
DS 43 Delegation Signer [RFC4034][RFC3658]
SSHFP 44 SSH Key Fingerprint [RFC4255]
RRSIG 46 RRSIG [RFC4034][RFC3755]
NSEC 47 NSEC [RFC4034][RFC3755]
NSEC3 50 NSEC3 [RFC5155]
TLSA 52 TLSA [RFC6698]
SMIMEA 53 S/MIME cert association [draft-ietf-dane-smime] SMIMEA/smimea-completed-template 2015-12-01
Unassigned 54
HIP 55 Host Identity Protocol [RFC5205]
NINFO 56 NINFO [Jim_Reid] NINFO/ninfo-completed-template 2008-01-21
RKEY 57 RKEY [Jim_Reid] RKEY/rkey-completed-template 2008-01-21
TALINK 58 Trust Anchor LINK [Wouter_Wijngaards] TALINK/talink-completed-template 2010-02-17
CDS 59 Child DS [RFC7344] CDS/cds-completed-template 2011-06-06
CDNSKEY 60 DNSKEY(s) the Child wants reflected in DS [RFC7344] 2014-06-16
OPENPGPKEY 61 OpenPGP Key [draft-ietf-dane-openpgpkey] OPENPGPKEY/openpgpkey-completed-template 2014-08-12
CSYNC 62 Child-To-Parent Synchronization [RFC7477] 2015-01-27
Unassigned 63-98
SPF 99 [RFC7208]
UINFO 100 [IANA-Reserved]
UID 101 [IANA-Reserved]
GID 102 [IANA-Reserved]
UNSPEC 103 [IANA-Reserved]
NID 104 [RFC6742] ILNP/nid-completed-template
L32 105 [RFC6742] ILNP/l32-completed-template
L64 106 [RFC6742] ILNP/l64-completed-template
LP 107 [RFC6742] ILNP/lp-completed-template
EUI48 108 an EUI-48 address [RFC7043] EUI48/eui48-completed-template 2013-03-27
EUI64 109 an EUI-64 address [RFC7043] EUI64/eui64-completed-template 2013-03-27
Unassigned 110-248
TKEY 249 Transaction Key [RFC2930]
TSIG 250 Transaction Signature [RFC2845]
IXFR 251 incremental transfer [RFC1995]
AXFR 252 transfer of an entire zone [RFC1035][RFC5936]
MAILB 253 mailbox-related RRs (MB, MG or MR) [RFC1035]
MAILA 254 mail agent RRs (OBSOLETE – see MX) [RFC1035]
* 255 A request for all records the server/cache has available [RFC1035][RFC6895]
URI 256 URI [RFC7553] URI/uri-completed-template 2011-02-22
CAA 257 Certification Authority Restriction [RFC6844] CAA/caa-completed-template 2011-04-07
Unassigned 258-32767
TA 32768 DNSSEC Trust Authorities [Sam_Weiler][][ Deploying DNSSEC Without a Signed Root. Technical Report 1999-19, Information Networking Institute, Carnegie Mellon University, April 2004.] 2005-12-13
DLV 32769 DNSSEC Lookaside Validation [RFC4431]
Unassigned 32770-65279
Private use 65280-65534
Reserved 65535