B-2
User Guide for Cisco Network Registrar, 7.1
OL-16002-01
Part 6
Appendices, Glossary, and Index
Appendix B DHCP Options
Option Descriptions
Table B-1
RFC 1497 Vendor Extension Options
Option Name
No. Length
Description
Pad
0
1 octet
Causes the subsequent fields to align on word boundaries.
End
255 1 octet
End of valid information in the vendor field. Subsequent
octets should be filled with the Pad options.
Subnet Mask
1
4 octets
Client subnet mask, as per RFC 950. If both the Subnet Mask
and the Router option are specified in a DHCP reply, the
Subnet Mask option must be first.
Time Offset
2
4 octets
Offset of the client subnet, in seconds, from Universal Time
(UT). The offset is expressed as a twos-complement 32-bit
integer. A positive offset indicates a location east of the zero
meridian and a negative offset indicates a location west of the
zero meridian.
Router
3
4 octet minimum;
multiples of 4
List of IP addresses for routers on the client subnet. Routers
should be in order of preference.
Time Server
4
4 octet minimum;
multiples of 4
List of RFC 868 compliant time servers available to the
client. Servers should be in order of preference.
Name Server
Option
5
4 octet minimum;
multiples of 4
List of IEN 116 name servers available to the client. Servers
should be in order of preference.
Domain Name
Server
6
4 octet minimum;
multiples of 4
List of Domain Name System (STD 13, RFC 1035) name
servers available to the client. Servers should be in order of
preference.
Log Server
7
4 octet minimum;
multiples of 4
List of MIT-LCS UDP log servers available to the client.
Servers should be in order of preference.
Cookie Server 8
4 octet minimum;
multiples of 4
List of RFC 865-compliant cookie servers available to the
client. Servers should be in order of preference.
LPR Server
9
4 octet minimum;
multiples of 4
List of RFC 1179-compliant line printer servers available to
the client. Servers should be in order of preference.
Impress
Server
10
4 octet minimum;
multiples of 4
List of Imagen Impress servers available to the client. Servers
should be in order of preference.
Resource
Location
Server
11
4 octet minimum;
multiples of 4
List of RFC 887-compliant resource location servers
available to the client. Servers should be in order of
preference.
Host Name
12
1 octet minimum
Name of the client. The name may or may not be qualified
with the local domain name. See RFC 1035 for the character
set restrictions.
Boot File Size 13
2 octets
Number of 512-octet blocks in the default boot file.
Merit Dump
File
14
1 octet minimum
Path name of a file to which the client core image should be
placed in the event the client crashes. The path is formatted
as a character string consisting of characters from the NVT
ASCII character set.
Domain Name 15
1 octet minimum
Domain name that the client should use when resolving
hostnames through the Domain Name System.
Swap Server
16
4 octets
IP address of the client swap server.
