[LEDE-DEV] DNS split horizon *without* dnsmasq

[Eric Luehrsen]

It seems I have static-stub wrong for its purpose. dhcpd and bind do 
work together. To accomplish this, the bind instance needs to be master 
for the domain zone and ptr zone where DHCP records will be entered. 
This master zone needs to permit remote updates, preferably with a 
secure key. dhcpd needs to be configure to dynamically update DNS 
through binds remote control, again with the key if configured.

dhcpd reference conf to get started, incomplete
```||
|ddns-update-style standard;|||
|ddns-rev-domainname "in-addr.arpa.";|||
||
|zone openwrt.lan. {|
|||   # where to send updates for hostid.openwrt.lan|
|   primary 127.0.0.1; };|
||
|zone 1.168.192.in-addr.arpa. {|
|   primary 127.0.0.1; }|;
||
|```|
||
bind reference conf to get started, incomplete
https://ftp.isc.org/isc/bind9/cur/9.9/doc/arm/Bv9ARM.ch06.html#dynamic_update_policies
```||
|zone "|||openwrt.lan|" { |
|  type master;|
|  file "/var/lib/bind/||||db.openwrt.lan||"; |
|  update-policy {
     # you can restrict record types, rather than "any"
||    grant [key-name] zonesub any; |
|  }; |
|}; |
||
|zone "1.168.192.in-addr.arpa" {|
|  type master;|
|  file "|||/var/lib/bind|/db.1.168.192.in-addr.arpa";|
|  update-policy {|
|    grant [key-name] zonesub any;|
|  };|
|};|
```


Both could include a key file like
```||
|key "key-name" { |
|  algorithm [hash];
   secret "passphrase"; };|
```