2.2.4.1.2 DNS_NAME_CHECK_FLAGS

The DNS server enforces different levels of syntax checking for FQDNs. DNS_NAME_CHECK_FLAGS is a DWORD value that specifies the configured level of syntax checking for FQDNs. DNS [RFC1034] and [RFC2181] requires that all FQDNs meet the following basic criteria:

  • Total length no longer than 255 characters.

  •  Each label is less than 63 characters.

  • No two consecutive "." characters.

The name check value MUST be set to one of the following allowed values to modify basic FQDN validity checking:

Constant/value

Description

DNS_ALLOW_RFC_NAMES_ONLY

0x00000000

The DNS server accepts FQDNs that only contain the ASCII characters "a-z", "A-Z", and "0-9". Names that begin with "." or contain two consecutive "." characters are rejected. The name can contain zero or one "*", but this character MUST appear as the first character in the name if it is present.

DNS_ALLOW_NONRFC_NAMES

0x00000001

The DNS server accepts any printable ASCII character in an FQDN.

DNS_ALLOW_MULTIBYTE_NAMES

0x00000002

The DNS server accepts all characters specified above and also UTF-8 [RFC3629] characters in FQDNs.

DNS_ALLOW_ALL_NAMES

0x00000003

The DNS server does not restrict the set of characters that appear in FQDNs.

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