Odhcpd and dnsmasq configuration confusion

[yjhn]

Currently, it is not clear how to configure DHCPv6 and SLAAC, because the wiki has two pages for this:

• (1) https://openwrt.org/docs/guide-user/base-system/dhcp
• (2) https://openwrt.org/docs/techref/odhcpd

These pages have conflicting information. For example, ra_management in (1) and ra_flags in (2). They are similar, but ra_management does not allow controlling other-config RA flag. Also in (1) it is not specified whether dnsmasq or odhcpd is used for RA messages. Also, dns and ra_slaac options are missing from (1).

So my questions are:

1. Is odhcpd used for everything IPv6 related (including RA)?
2. Should ra_management or ra_flags be used? It appears that ra_flags take precendence, because they are configured in 21.02. Then why does ra_management option exist?
3. (somewhat unrelated) What does ra_slaac option control exactly? Does it control the A flag in RA or something else?
4. (also unrelated) Can odhcpd work as a DNS server? Because there is an option dns_service, which announces the router as a DNS server. Or is another DNS server (dnsmasq) supposed to be running?

[yjhn]

I found my answers after digging in odhcpd source code:

1. It appears so, so I assume yes.
2. ra_flags and ra_slaac supersede ra_management, ra_management is deprecated
3. ra_slaac just sets the A flag in RA messages, this allows clients to use SLAAC to generate addresses.
4. odhcpd is not a DNS server. When dns_service is set, it simply tells clients that there is a DNS server on the router. It is a user's responsibility to set up a DNS server.