Update FAQ to fix a couple of dead links.

Thanks to Federico Bianchi for reporting this.

FAQ

@@ -320,8 +320,18 @@ A: Yes, new releases of dnsmasq are always announced through
 
 Q: What does the dhcp-authoritative option do? 
 
-A: See http://www.isc.org/files/auth.html - that's
-   for the ISC daemon, but the same applies to dnsmasq.
+A: The DHCP spec says that when a DHCP server recieves a renewal request
+   from a client it has no knowledge of, it should just ignore it.
+   This is because it's supported to have more than one DHCP server
+   on a network, and another DHCP server may be dealing with the client.
+   This has the unfortunate effect that when _no_ DHCP replies to 
+   the client, it takes some time for the client to time-out and start 
+   to get a new lease. Setting this option makes dnsmasq violate the
+   standard to the extent that it will send a NAK reply to the client, 
+   causing it to immediately start to get a new lease. This improves 
+   behaviour when machines move networks, and in the case that the DHCP
+   lease database is lost. As long as there are not more tha one DHCP
+   server on the network, it's safe to enable the option.
 
 Q: Why does my Gentoo box pause for a minute before getting a new
    lease?
@@ -349,6 +359,7 @@ A: By default, the identity of a machine is determined by using the
    method for setting the client-id varies with DHCP client software,
    dhcpcd uses the "-I" flag. Windows uses a registry setting,
    see http://www.jsiinc.com/SUBF/TIP2800/rh2845.htm
+
 Addendum:
    From version 2.46, dnsmasq has a solution to this which doesn't
    involve setting client-IDs. It's possible to put more than one MAC
@@ -361,6 +372,51 @@ Addendum:
    constraint: if you configure multiple MAC addresses and violate 
    this rule, bad things will happen.
 
+Addendum-II: The link above is dead, the former contents of the link are:
+
+------------------------------------------------------------------------------
+How can I keep the same DHCP client reservation, if the MAC address changes?
+
+When you reserve an IP address for a DHCP client, you provide the
+MAC address of the client's NIC.
+
+It is possible to use a custom identifier, which is sent as 
+option 61 in the client's DHCP Discover and Request packet.
+
+The DhcpClientIdentifier is a REG_DWORD value that is located at:
+
+Windows NT 4.0 SP2+
+
+HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\<Adapter Name>'X'\Parameters\Tcpip
+
+where <Adapter Name> is the NIC driver name and 'X' is the number of the NIC.
+
+Windows 2000
+
+HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\TcpIp\Parameters\Interfaces\<NIC GUID>
+
+where <NIC GUID> is the GUID of the NIC.
+
+The valid range of data is 0x0 - 0xFFFFFFFF. The custom identifier is send as 4 bytes, 
+8 hexadecimal character, in groups of 2 hexadecimal characters, with the groups being 
+sent in reverse order. If the custom identifier is less than 8 hexadeciaml characters, 
+it is zero padded at the end. Examples:
+
+Custom Client                 Client Reservation
+Identifier                    on DHCP Server
+12345678                      78563412
+123456                        56341200
+1234                          34120000
+1234567                       67452301
+12345                         45230100
+123                           23010000
+A18F42                        428FA100
+CF432                         32F40C00
+C32D1BE                       BED1320C
+
+-------------------------------------------------------------------------------------------------------
+
+
 Q: Can dnsmasq do DHCP on IP-alias interfaces?
 
 A: Yes, from version-2.21. The support is only available running under