Merge pull request #446 from DrDoof/feat/dns

dns: resolve host names

doc/dns.md

@@ -0,0 +1,23 @@
+# DNS
+
+The switch can resolve host names to IPv4 addresses, for the NTP client and
+for anything else that is given a name instead of an address.
+
+```
+dns server <ip> [<ip>]   # one or two servers, 0.0.0.0 removes them
+dns lookup <name>        # resolve a name and print the address
+dns                      # show the servers and the last lookup
+```
+
+The answer to a lookup arrives after the command has returned, so it is
+printed on the serial console and in the syslog. In the console of the web
+interface, run `dns` afterwards to see it.
+
+Without a configured server the resolver uses the one handed out by DHCP.
+Only address records are looked up; a query goes to the servers in turn,
+every two seconds, and gives up after six tries. A name that already is a
+dotted address is taken as it is, without a query.
+
+The DNS servers are set in the Network card of the System page as well.
+Settings made there or on the console are kept only once the configuration is
+saved.