diff --git a/src/lib/dhcp/duid.h b/src/lib/dhcp/duid.h
index fe642f4dd26c4cf2fb6479522872cdb275c8d3e5..1b75f73ebf85454d830d46eeaff85cc438b5961e 100644
--- a/src/lib/dhcp/duid.h
+++ b/src/lib/dhcp/duid.h
@@ -91,6 +91,11 @@ public:
     /// @brief Maximum size of a client ID
     ///
     /// This is the same as the maximum size of the underlying DUID.
+    ///
+    /// @note RFC 2131 does not specify an upper length of a client ID, the
+    ///       value chosen here just being that of the underlying DUID.  For
+    ///       some backend database, there may be a possible (minor)
+    ///       performance enhancement if this were smaller.
     static const size_t MAX_CLIENT_ID_LEN = DUID::MAX_DUID_LEN;
 
     /// @brief Constructor based on vector<uint8_t>
diff --git a/src/lib/dhcpsrv/mysql_lease_mgr.h b/src/lib/dhcpsrv/mysql_lease_mgr.h
index be86c3a15f341282077495557575a32ffd15e2fa..8a97fc07738594e0297ea35bc2121fa348ffb034 100644
--- a/src/lib/dhcpsrv/mysql_lease_mgr.h
+++ b/src/lib/dhcpsrv/mysql_lease_mgr.h
@@ -110,7 +110,7 @@ public:
     /// @brief Returns an IPv4 lease for specified IPv4 address
     ///
     /// This method return a lease that is associated with a given address.
-    /// For other query types (by hardware addr, by DUID) there can be
+    /// For other query types (by hardware addr, by Client ID) there can be
     /// several leases in different subnets (e.g. for mobile clients that
     /// got address in different subnets). However, for a single address
     /// there can be only one lease, so this method returns a pointer to