Code

Option name

Meaning

0

Pad

Causes subsequent fields to align on word boundaries.

255

End

Indicates end of options in the DHCP packet.

1

Subnet mask

Specifies the subnet mask of the client subnet. This option is defined in the Create Scope or Scope Properties dialog box. It cannot be set directly in an Option dialog box.

2

Time offset

Specifies the Universal Coordinated Time (UCT) offset in seconds.

3

Router

Specifies a list of IP addresses for routers on the client's subnet.1

4

Time server

Specifies a list of IP addresses for time servers available to the client.1

5

Name servers

Specifies a list of IP addresses for name servers available to the client.1

6

DNS servers

Specifies a list of IP addresses for DNS name servers available to the client.1 Multihomed computers can have only one list per computer, not one per adapter card.

7

Log servers

Specifies a list of IP addresses for MIT_LCS User Datagram Protocol (UDP) log servers available to the client.1

8

Cookie servers

Specifies a list of IP addresses for RFC 865 cookie servers available to the client.1

9

LPR servers

Specifies a list of IP addresses for RFC 1179 line-printer servers available to the client.1

10

Impress servers

Specifies a list of IP addresses for Imagen Impress servers available to the client.1

11

Resource location servers

Specifies a list of RFC 887 Resource Location servers available to the client.1

12

Host name

Specifies the host name of up to 63 characters for the client. The name must start with a letter, end with a letter or digit, and have as interior characters only letters, numbers, and hyphens. The name can be qualified with the local DNS domain name.

13

Boot file size

Specifies the size of the default boot image file for the client, in 512-octet blocks.

14

Merit dump file

Specifies the ASCII path name of a file where the client's core image is dumped if a crash occurs.

15

Domain name

Specifies the DNS domain name the client should use for DNS host name resolution.

16

Swap server

Specifies the IP address of the client's swap server.

17

Root path

Specifies the ASCII path name for the client's root disk.

18

Extensions path

Specifies a file retrievable via TFTP containing information interpreted the same as the vendor-extension field in the BOOTP response, except the file length is unconstrained and references to Tag 18 in the file are ignored.

Code

Option name

Meaning

19

IP layer forwarding

Enables or disables forwarding of IP packet for this client. 1 enables forwarding; 0 disables it.

20

Nonlocal source routing

Enables or disables forwarding of datagrams with nonlocal source routes. 1 enables forwarding; 0 disables it.

21

Policy filter masks

Specifies policy filters that consist of a list of pairs of IP addresses and masks specifying destination/mask pairs for filtering nonlocal source routes. Any source routed datagram whose next-hop address does not match a filter will be discarded by the client.

22

Max DG reassembly size

Specifies the maximum size datagram that the client can reassemble. The minimum value is 576.

23

Default time-to-live

Specifies the default time-to-live (TTL) that the client uses on outgoing datagrams. The value for the octet is a number between 1 and 255.

24

Path MTU aging timeout

Specifies the timeout in seconds for aging Path Maximum Transmission Unit (MTU) values (discovered by the mechanism defined in RFC 1191).

25

Path MTU plateau table

Specifies a table of MTU sizes to use when performing Path MTU Discovered as defined in RFC 1191. The table is sorted by size from smallest to largest. The minimum MTU value is 68.

Code

Option name

Meaning

26

MTU option

Specifies the MTU discovery size for this interface. The minimum MTU value is 68.

27

All subnets are local

Specifies whether the client assumes that all subnets of the client's internetwork use the same MTU as the local subnet where the client is connected. 1 indicates that all subnets share the same MTU; 0 indicates that the client should assume some subnets might have smaller MTUs.

28

Broadcast address

Specifies the broadcast address used on the client's subnet.

29

Perform mask discovery

Specifies whether the client should use Internet Control Message Protocol (ICMP) for subnet mask discovery. 1 indicates the client should perform mask discovery; 0 indicates the client should not.

30

Mask supplier

Specifies whether the client should respond to subnet mask requests using ICMP. 1 indicates the client should respond; 0 indicates the client should not respond.

31

Perform router discovery

Specifies whether the client should solicit routers using the router discovery method in RFC 1256. 1 indicates that the client should perform router discovery; 0 indicates that the client should not use it.

32

Router solicitation address

Specifies the IP address to which the client submits router solicitation requests.

33

Static route

Specifies a list of IP address pairs that indicate the static routes the client should install in its routing cache. Any multiple routes to the same destination are listed in descending order or priority. The routes are destination/router address pairs. (The default route of 0.0.0.0 is an illegal destination for a static route.)

Code

Option name

Meaning

34

Trailer encapsulation

Specifies whether the client should negotiate use of trailers (RFC 983) when using the ARP protocol. 1 indicates the client should attempt to use trailer; 0 indicates the client should not use trailers.

35

ARP cache timeout

Specifies the timeout in seconds for ARP cache entries.

36

Ethernet encapsulation

Specifies whether the client should use Ethernet v. 2 (RFC 894) or IEEE 802.3 (RFC 1042) encapsulation if the interface is Ethernet. 1 indicates that the client should use RFC 1042 encapsulation; 0 indicates the client should use RFC 894 encapsulation.

Code

Option name

Meaning

37

Default time-to-live

Specifies the default TTL the client should use when sending TCP segments. The minimum value of the octet is 1.

38

Keepalive interval

Specifies the interval in seconds the client TCP should wait before sending a keepalive message on a TCP connection. A value of 0 indicates that the client should not send keepalive messages on connections unless specifically requested by an application.

39

Keepalive garbage

Specifies whether the client should send TCP keepalive messages with an octet of garbage data for compatibility with older implementations. 1 indicates that a garbage octet should be sent; 0 indicates that it should not be sent.

Code

Option name

Meaning

40

NIS domain name

Specifies the name of the Network Information Service (NIS) domain as an ASCII string.

41

NIS servers

Specifies a list of IP addresses for NIS servers available to the client.1

42

NTP servers

Specifies a list of IP addresses for Network Time Protocol (NTP) servers available to the client.1

Code

Option name

Meaning

43

Vendor specific info

Binary information used by clients and servers to exchange vendor-specific information. Servers not equipped to interpret the information ignore it. Clients that don't receive the information attempt to operate without it.

Code

Option name

Meaning

44

WINS/NBNS servers

Specifies a list of IP addresses for NetBIOS name servers (NBNS).1

45

NetBIOS over TCP/IP NBDD

Specifies a list of IP addresses for NetBIOS datagram distribution servers (NBDD).1

46

WINS/NBT node type

Allows configurable NetBIOS over TCP/IP clients to be configured as described in RFC 1001/1002, where 1=b-node, 2=p-node, 4=m-node, and 8=h-node. On multihomed computers, the node type is assigned to the entire computer, not to individual adapter cards.

47

NetBIOS scope ID

Specifies as a string that is the NetBIOS over TCP/IP Scope ID for the client, as specified in RFC 1001/1002. On multihomed computers, the scope ID is assigned to the entire computer, not to individual adapter cards.

48

X Window system font

Specifies a list of IP addresses for X Window font servers available to the client.1

49

X Window system display

Specifies a list of IP addresses for X Window System Display Manager servers available to the client.1

Code

Option name

Meaning

51

Lease time

Specifies the time in seconds from address assignment until the client's lease on the address expires. Lease time is specified in the Create Scope or Scope Properties dialog box. It cannot be set directly in a DHCP Options dialog box.

58

Renewal (T1) time value

Specifies the time in seconds from address assignment until the client enters the renewing state. Renewal time is a function of the lease time option, which is specified in the Create Scope or Scope Properties dialog box. It cannot be set directly in a DHCP Options dialog box.

59

Rebinding (T2) time value

Specifies the time in seconds from address assignment until the client enters the rebinding state. Rebinding time is a function of the lease time option, which is specified in the Create Scope or Scope Properties dialog box. It cannot be set directly in a DHCP Options dialog box.