A. 选项在消息类型中的出现位置 (Appearance of Options in Message Types)

下表用 "*" 表示每种 DHCP message type 中允许出现的 options:

        Client Server IA_NA  Option Pref  Time Relay Auth. Server
          ID     ID   IA_TA  Request            Msg.       Unica.
Solicit   *             *      *           *           *
Advert.   *      *      *            *                 *
Request   *      *      *      *           *           *
Confirm   *             *      *           *           *
Renew     *      *      *      *           *           *
Rebind    *             *      *           *           *
Decline   *      *      *      *           *           *
Release   *      *      *      *           *           *
Reply     *      *      *            *                 *     *
Reconf.   *      *             *                       *
Inform.   * (see note)         *           *           *
R-forw.                                          *     *
R-repl.                                          *     *

NOTE:

仅包含在为响应 Reconfigure 而发送的 Information-Request 消息中 (见第 19.4.3 节).

         Status  Rap. User  Vendor Vendor Inter. Recon. Recon.
          Code  Comm. Class Class  Spec.    ID    Msg.  Accept
Solicit           *     *     *      *                    *
Advert.    *            *     *      *                    *
Request                 *     *      *                    *
Confirm                 *     *      *
Renew                   *     *      *                    *
Rebind                  *     *      *                    *
Decline                 *     *      *
Release                 *     *      *
Reply      *      *     *     *      *                    *
Reconf.                                            *
Inform.                 *     *      *                    *
R-forw.                 *     *      *      *
R-repl.                 *     *      *      *