Windows 2000 DNS |
Different DNS implementations impose different character and length restrictions. Table 6.2 shows the restrictions for each implementation.
Table 6.2 Name Restrictions
Restriction |
Standard DNS (Including Windows NT 4.0) | DNS in Windows 2000 |
NetBIOS |
---|---|---|---|
Characters | Supports RFC 1123, which permits "A" to "Z", "a" to "z", "0" to "9", and the |
Several different configurations are possible, as described at the end of this section. | Unicode characters, numbers, white space, symbols: ! @ # $ % ^ & ' ) ( . - _ { } ~ |
Fully qualified domain name length | 63 bytes per label and 255 bytes for an FQDN | 63 bytes per label and 255 bytes for an FQDN; The FQDN for an Active Directory domain name is limited to 64 bytes. | 15 bytes |
Update
The print version of this book states that fully qualified domain name lengths are "63 bytes per label and 255 bytes for an FQDN; domain controllers are limited to 155 bytes for an FQDN." The previous table in this online version contains more up-to-date information.
Note
Although you can create long, complex DNS names, it is recommended that you create shorter, user-friendly names.
According to RFC 1123, the only characters that can be used in DNS labels are "A" to "Z", "a" to "z", "0" to "9", and the hyphen
However, adherence to RFC 1123 can present a problem on Windows 2000 networks that still use NetBIOS names. NetBIOS names can use additional characters, and it can be time consuming to convert all the NetBIOS names to standard DNS names.
To simplify the migration process to Windows 2000 from Windows NT 4.0, Windows 2000 supports a wider character set. RFC 2181, "Clarifications to the DNS Specification," enlarges the character set allowed in DNS names. It states that a DNS label can be any binary string, and it does not necessarily need to be interpreted as ASCII. Based on this definition, Microsoft has proposed that the DNS name specification be readjusted to accommodate a larger character set:
However, before using additional characters, consider the following issues:
You can configure the Windows 2000 DNS server to allow or disallow the use of
Note
If you enter a DNS name that includes