B-6
User Guide for Cisco Network Registrar, 7.1
OL-16002-01
Appendices, Glossary, and Index
Appendix B DHCP Options
Option Descriptions
Network Time
Protocol Servers
42
4 octet minimum;
multiples of 4
List of IP addresses indicating NTP servers that are
available to the client. Servers should be in order of
preference.
Vendor-Specific
Information
43
1 octet minimum
This option is used by clients and servers to exchange
vendor-specific information. The information is an opaque
object of
n
octets, presumably interpreted by
vendor-specific code on the clients and servers. The
definition of this information is vendor specific. The
vendor is indicated in the
dhcp-class-identifier
option.
Servers not equipped to interpret the vendor-specific
information sent by a client must ignore it (although it can
be reported). Clients that do not receive desired
vendor-specific information should make an attempt to
operate without it, although they can do so (and announce
they are doing so) in a degraded mode.
If a vendor potentially encodes more than one item of
information in this option, then the vendor should encode
the option using encapsulated vendor-specific options as
described here.
The encapsulated vendor-specific options field should be
encoded as a sequence of code, length, and value fields of
identical syntax to the DHCP options field with these
exceptions:
•
There should not be a magic cookie field in the
encapsulated vendor-specific extensions field.
•
Codes other than 0 or 255 can be redefined by the
vendor within the encapsulated vendor-specific
extensions field, but should conform to the
tag-length-value syntax defined in section 2.
Code 255 (END), if present, signifies the end of the
encapsulated vendor extensions, not the end of the vendor
extensions field.
If the code 255 is not present, then the end of the enclosing
vendor-specific information field is taken as the end of the
encapsulated vendor-specific extensions field.
NetBIOS over
TCP/IP Name
Server
44
4 octet minimum;
multiples of 4
List of RFC 1001/1002 NBNS name servers in order of
preference.
NetBIOS over
TCP/IP
Datagram
Distribution
Server
45
4 octet minimum;
multiples of 4
List of RFC 1001/1002 NBDD servers in order of
preference.
Table B-6
Application and Service Parameter Options (continued)
Option Name
No. Length
Description
