{"id":4276,"date":"2026-04-29T15:25:53","date_gmt":"2026-04-29T19:25:53","guid":{"rendered":"https:\/\/increasec.com\/?p=4276"},"modified":"2026-04-29T15:26:29","modified_gmt":"2026-04-29T19:26:29","slug":"unifi-dhcp-option-43-deets","status":"publish","type":"post","link":"https:\/\/increasec.com\/?p=4276","title":{"rendered":"Unifi DHCP Option 43 deets"},"content":{"rendered":"\n

this is used to get Unifi devices to (Inform? announce themselves?) across VLANs<\/p>\n\n\n\n

chrkov
14 years ago<\/p>\n\n\n\n

I dont think that the option 43 being in HEX is ubiquiti’s choice, its just the way option 43 in DHCP was designed. I think I have a grip on it.<\/p>\n\n\n\n

If I am understanding this correctly, you design the hex code as follows:<\/p>\n\n\n\n

0104C0A89602<\/p>\n\n\n\n

The 01 is always 01 for the UBNT equipment<\/p>\n\n\n\n

The 04 is for a single IP.<\/p>\n\n\n\n

The C0A89602 is your IP in HEX. In this case, C0 is 192, A8 is 168, 96 is 150 and 02 is 2.<\/p>\n\n\n\n

You can use the Windows Calc to convert DEC to HEX very easily.<\/p>\n\n\n\n

Then go to your Microsoft DHCP server:<\/p>\n\n\n\n

    \n
  1. Right Click Server Options and then configure options.<\/li>\n\n\n\n
  2. Click Option 43<\/li>\n\n\n\n
  3. Enter your HEX code in the Binary Field.<\/li>\n\n\n\n
  4. Click OK and your done.<\/li>\n<\/ol>\n\n\n\n

    Someone or anyone correct me if I am wrong.
    4<\/p>\n\n\n\n

    Note: I would typically make Option 43 a Server Option<\/strong>, then it will be a default for every VLAN, make a option 43 for a specific vlan to overwrite.<\/p>\n\n\n\n

    source https:\/\/community.ui.com\/questions\/DHCP-Option-43\/59fb8337-bfa1-4b7d-8e95-3780d10c3603?reply=8<\/a><\/p>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    this is used to get Unifi devices to (Inform? announce themselves?) across VLANs chrkov14 years ago I dont think that the option 43 being in HEX is ubiquiti’s choice, its…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[173,212],"class_list":["post-4276","post","type-post","status-publish","format-standard","hentry","category-uncategorised","tag-networking","tag-unifi"],"_links":{"self":[{"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/posts\/4276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/increasec.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4276"}],"version-history":[{"count":2,"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/posts\/4276\/revisions"}],"predecessor-version":[{"id":4278,"href":"https:\/\/increasec.com\/index.php?rest_route=\/wp\/v2\/posts\/4276\/revisions\/4278"}],"wp:attachment":[{"href":"https:\/\/increasec.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/increasec.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/increasec.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}