Tag Name Data Length Meaning Reference 
1Subnet Mask4Subnet Mask Value[RFC2132]
2Time Offset4Time Offset in Seconds from UTC (note: deprecated by 100 and 101)[RFC2132]
3RouterNN/4 Router addresses[RFC2132]
4Time ServerNN/4 Timeserver addresses[RFC2132]
5Name ServerNN/4 IEN-116 Server addresses[RFC2132]
6Domain ServerNN/4 DNS Server addresses[RFC2132]
7Log ServerNN/4 Logging Server addresses[RFC2132]
8Quotes ServerNN/4 Quotes Server addresses[RFC2132]
9LPR ServerNN/4 Printer Server addresses[RFC2132]
10Impress ServerNN/4 Impress Server addresses[RFC2132]
11RLP ServerNN/4 RLP Server addresses[RFC2132]
12HostnameNHostname string[RFC2132]
13Boot File Size2Size of boot file in 512 byte chunks[RFC2132]
14Merit Dump FileNClient to dump and name the file to dump it to[RFC2132]
15Domain NameNThe DNS domain name of the client[RFC2132]
16Swap ServerNSwap Server address[RFC2132]
17Root PathNPath name for root disk[RFC2132]
18Extension FileNPath name for more BOOTP info[RFC2132]
19Forward On/Off1Enable/Disable IP Forwarding[RFC2132]
20SrcRte On/Off1Enable/Disable Source Routing[RFC2132]
21Policy FilterNRouting Policy Filters[RFC2132]
22Max DG Assembly2Max Datagram Reassembly Size[RFC2132]
23Default IP TTL1Default IP Time to Live[RFC2132]
24MTU Timeout4Path MTU Aging Timeout[RFC2132]
25MTU PlateauNPath MTU Plateau Table[RFC2132]
26MTU Interface2Interface MTU Size[RFC2132]
27MTU Subnet1All Subnets are Local[RFC2132]
28Broadcast Address4Broadcast Address[RFC2132]
29Mask Discovery1Perform Mask Discovery[RFC2132]
30Mask Supplier1Provide Mask to Others[RFC2132]
31Router Discovery1Perform Router Discovery[RFC2132]
32Router Request4Router Solicitation Address[RFC2132]
33Static RouteNStatic Routing Table[RFC2132]
34Trailers1Trailer Encapsulation[RFC2132]
35ARP Timeout4ARP Cache Timeout[RFC2132]
36Ethernet1Ethernet Encapsulation[RFC2132]
37Default TCP TTL1Default TCP Time to Live[RFC2132]
38Keepalive Time4TCP Keepalive Interval[RFC2132]
39Keepalive Data1TCP Keepalive Garbage[RFC2132]
40NIS DomainNNIS Domain Name[RFC2132]
41NIS ServersNNIS Server Addresses[RFC2132]
42NTP ServersNNTP Server Addresses[RFC2132]
43Vendor SpecificNVendor Specific Information[RFC2132]
44NETBIOS Name SrvNNETBIOS Name Servers[RFC2132]
45NETBIOS Dist SrvNNETBIOS Datagram Distribution[RFC2132]
46NETBIOS Node Type1NETBIOS Node Type[RFC2132]
48X Window FontNX Window Font Server[RFC2132]
49X Window ManagerNX Window Display Manager[RFC2132]
50Address Request4Requested IP Address[RFC2132]
51Address Time4IP Address Lease Time[RFC2132]
52Overload1Overload “sname” or “file”[RFC2132]
53DHCP Msg Type1DHCP Message Type[RFC2132]
54DHCP Server Id4DHCP Server Identification[RFC2132]
55Parameter ListNParameter Request List[RFC2132]
56DHCP MessageNDHCP Error Message[RFC2132]
57DHCP Max Msg Size2DHCP Maximum Message Size[RFC2132]
58Renewal Time4DHCP Renewal (T1) Time[RFC2132]
59Rebinding Time4DHCP Rebinding (T2) Time[RFC2132]
60Class IdNClass Identifier[RFC2132]
61Client IdNClient Identifier[RFC2132]
62NetWare/IP DomainNNetWare/IP Domain Name[RFC2242]
63NetWare/IP OptionNNetWare/IP sub Options[RFC2242]
64NIS-Domain-NameNNIS+ v3 Client Domain Name[RFC2132]
65NIS-Server-AddrNNIS+ v3 Server Addresses[RFC2132]
66Server-NameNTFTP Server Name[RFC2132]
67Bootfile-NameNBoot File Name[RFC2132]
68Home-Agent-AddrsNHome Agent Addresses[RFC2132]
69SMTP-ServerNSimple Mail Server Addresses[RFC2132]
70POP3-ServerNPost Office Server Addresses[RFC2132]
71NNTP-ServerNNetwork News Server Addresses[RFC2132]
72WWW-ServerNWWW Server Addresses[RFC2132]
73Finger-ServerNFinger Server Addresses[RFC2132]
74IRC-ServerNChat Server Addresses[RFC2132]
75StreetTalk-ServerNStreetTalk Server Addresses[RFC2132]
76STDA-ServerNST Directory Assist. Addresses[RFC2132]
77User-ClassNUser Class Information[RFC3004]
78Directory AgentNdirectory agent information[RFC2610]
79Service ScopeNservice location agent scope[RFC2610]
80Rapid Commit0Rapid Commit[RFC4039]
81Client FQDNNFully Qualified Domain Name[RFC4702]
82Relay Agent InformationNRelay Agent Information[RFC3046]
83iSNSNInternet Storage Name Service[RFC4174]
85NDS ServersNNovell Directory Services[RFC2241]
86NDS Tree NameNNovell Directory Services[RFC2241]
87NDS ContextNNovell Directory Services[RFC2241]
88BCMCS Controller Domain Name list[RFC4280]
89BCMCS Controller IPv4 address option[RFC4280]
91client-last-transaction-time option[RFC4388]
92associated-ip option[RFC4388]
93Client SystemNClient System Architecture[RFC4578]
94Client NDINClient Network Device Interface[RFC4578]
95LDAPNLightweight Directory Access Protocol[RFC3679]
97UUID/GUIDNUUID/GUID-based Client Identifier[RFC4578]
98User-AuthNOpen Group’s User Authentication[RFC2485]
100PCodeNIEEE 1003.1 TZ String[RFC4833]
101TCodeNReference to the TZ Database[RFC4833]
109OPTION_DHCP4O6_S46_SADDR16DHCPv4 over DHCPv6 Softwire Source Address Option[RFC8539]
112Netinfo AddressNNetInfo Parent Server Address[RFC3679]
113Netinfo TagNNetInfo Parent Server Tag[RFC3679]
116Auto-ConfigNDHCP Auto-Configuration[RFC2563]
117Name Service SearchNName Service Search[RFC2937]
118Subnet Selection Option4Subnet Selection Option[RFC3011]
119Domain SearchNDNS domain search list[RFC3397]
120SIP Servers DHCP OptionNSIP Servers DHCP Option[RFC3361]
121Classless Static Route OptionNClassless Static Route Option[RFC3442]
122CCCNCableLabs Client Configuration[RFC3495]
123GeoConf Option16GeoConf Option[RFC6225]
124V-I Vendor ClassVendor-Identifying Vendor Class[RFC3925]
125V-I Vendor-Specific InformationVendor-Identifying Vendor-Specific Information[RFC3925]
128PXE – undefined (vendor specific)[RFC4578]
128Etherboot signature. 6 bytes: E4:45:74:68:00:00
128DOCSIS “full security” server IP address
128TFTP Server IP address (for IP Phone software load)
129PXE – undefined (vendor specific)[RFC4578]
129Kernel options. Variable length string
129Call Server IP address
130PXE – undefined (vendor specific)[RFC4578]
130Ethernet interface. Variable length string.
130Discrimination string (to identify vendor)
131PXE – undefined (vendor specific)[RFC4578]
131Remote statistics server IP address
132PXE – undefined (vendor specific)[RFC4578]
132IEEE 802.1Q VLAN ID
133PXE – undefined (vendor specific)[RFC4578]
133IEEE 802.1D/p Layer 2 Priority
134PXE – undefined (vendor specific)[RFC4578]
134Diffserv Code Point (DSCP) for VoIP signalling and media streams
135PXE – undefined (vendor specific)[RFC4578]
135HTTP Proxy for phone-specific applications
138OPTION_CAPWAP_AC_V4NCAPWAP Access Controller addresses[RFC5417]
139OPTION-IPv4_Address-MoSNa series of suboptions[RFC5678]
140OPTION-IPv4_FQDN-MoSNa series of suboptions[RFC5678]
141SIP UA Configuration Service DomainsNList of domain names to search for SIP User Agent Configuration[RFC6011]
142OPTION-IPv4_Address-ANDSFNANDSF IPv4 Address Option for DHCPv4[RFC6153]
143OPTION_V4_SZTP_REDIRECTNThis option provides a list of URIs for SZTP bootstrap servers[RFC8572]
144GeoLoc16Geospatial Location with Uncertainty[RFC6225]
145FORCERENEW_NONCE_CAPABLE1Forcerenew Nonce Capable[RFC6704]
146RDNSS SelectionNInformation for selecting RDNSS[RFC6731]
150TFTP server address[RFC5859]
150GRUB configuration path name
151status-codeN+1Status code and optional N byte text message describing status.[RFC6926]
152base-time4Absolute time (seconds since Jan 1, 1970) message was sent.[RFC6926]
153start-time-of-state4Number of seconds in the past when client entered current state.[RFC6926]
154query-start-time4Absolute time (seconds since Jan 1, 1970) for beginning of query.[RFC6926]
155query-end-time4Absolute time (seconds since Jan 1, 1970) for end of query.[RFC6926]
156dhcp-state1State of IP address.[RFC6926]
157data-source1Indicates information came from local or remote server.[RFC6926]
158OPTION_V4_PCP_SERVERVariable; the minimum length is 5.Includes one or multiple lists of PCP server IP addresses; each list is treated as a separate PCP server.[RFC7291]
159OPTION_V4_PORTPARAMS4This option is used to configure a set of ports bound to a shared IPv4 address.[RFC7618]
160DHCP Captive-PortalNDHCP Captive-Portal[RFC7710]
161OPTION_MUD_URL_V4N (variable)Manufacturer Usage Descriptions[RFC8520]
175Etherboot (Tentatively Assigned – 2005-06-23)
176IP Telephone (Tentatively Assigned – 2005-06-23)
177Etherboot (Tentatively Assigned – 2005-06-23)
177PacketCable and CableHome (replaced by 122)
208PXELINUX Magic4magic string = F1:00:74:7E[RFC5071][Deprecated]
209Configuration FileNConfiguration file[RFC5071]
210Path PrefixNPath Prefix Option[RFC5071]
211Reboot Time4Reboot Time[RFC5071]
212OPTION_6RD18 + NOPTION_6RD with N/4 6rd BR addresses[RFC5969]
213OPTION_V4_ACCESS_DOMAINNAccess Network Domain Name[RFC5986]
220Subnet Allocation OptionNSubnet Allocation Option[RFC6656]
221Virtual Subnet Selection (VSS) Option[RFC6607]
224-254Reserved (Private Use)