dnsdist: Doc: Clarify ECS a bit, fix the source address list

diff --git a/pdns/README-dnsdist.md b/pdns/README-dnsdist.md
index 1a1351a28e1cee1674c9d28cc4b3c5a09402e489..624b42f8c933922007c7211e3b1911566df77e24 100644 (file)
--- a/pdns/README-dnsdist.md
+++ b/pdns/README-dnsdist.md
@@ -140,11 +140,13 @@ newServer({address="192.0.2.1", checkType="AAAA", checkName="a.root-servers.net.
 ```
 
 In order to provide the downstream server with the address of the real client,
-or at least the one talking to `dnsdist`, the 'useClientSubnet' parameter can be used
+or at least the one talking to `dnsdist`, the `useClientSubnet` parameter can be used
 when declaring a new server. This parameter indicates whether an EDNS Client Subnet option
 should be added to the request. If the incoming request already contains an EDNS Client Subnet value,
-it will not be overriden unless `setECSOverride()` is set to true. The source prefix-length may be
-configured with:
+it will not be overriden unless `setECSOverride()` is set to true.
+The default source prefix-length is 24 for IPv4 and 56 for IPv6, meaning that for a query
+received from 192.0.2.42, the EDNS Client Subnet value sent to the backend will
+be 192.0.2.0. This can be changed with:
 ```
 > setECSSourcePrefixV4(24)
 > setECSSourcePrefixV6(56)
@@ -182,6 +184,7 @@ newServer({address="192.0.2.1", source="192.0.2.127@eth1"})
 ```
 
 The supported values for `source` are:
+
  * an IPv4 or IPv6 address, which must exist on the system
  * an interface name
  * an IPv4 or IPv6 address followed by '@' then an interface name