diff --git a/src/core/net/dns_client.cpp b/src/core/net/dns_client.cpp
index 48f6d5066..8aeac5999 100644
--- a/src/core/net/dns_client.cpp
+++ b/src/core/net/dns_client.cpp
@@ -48,30 +48,6 @@ using ot::Encoding::BigEndian::HostSwap16;
 namespace ot {
 namespace Dns {
 
-QueryMetadata::QueryMetadata(void)
-    : mHostname(nullptr)
-    , mResponseHandler(nullptr)
-    , mResponseContext(nullptr)
-    , mTransmissionTime()
-    , mDestinationPort(0)
-    , mRetransmissionCount(0)
-{
-    mSourceAddress.Clear();
-    mDestinationAddress.Clear();
-}
-
-QueryMetadata::QueryMetadata(otDnsResponseHandler aHandler, void *aContext)
-    : mHostname(nullptr)
-    , mResponseHandler(aHandler)
-    , mResponseContext(aContext)
-    , mTransmissionTime()
-    , mDestinationPort(0)
-    , mRetransmissionCount(0)
-{
-    mSourceAddress.Clear();
-    mDestinationAddress.Clear();
-}
-
 Client::Client(Instance &aInstance)
     : mSocket(aInstance)
     , mMessageId(0)
@@ -112,7 +88,7 @@ otError Client::Stop(void)
 otError Client::Query(const otDnsQuery *aQuery, otDnsResponseHandler aHandler, void *aContext)
 {
     otError                 error;
-    QueryMetadata           queryMetadata(aHandler, aContext);
+    QueryMetadata           queryMetadata;
     Message *               message     = nullptr;
     Message *               messageCopy = nullptr;
     Header                  header;
@@ -140,10 +116,12 @@ otError Client::Query(const otDnsQuery *aQuery, otDnsResponseHandler aHandler, v
     messageInfo = static_cast<const Ip6::MessageInfo *>(aQuery->mMessageInfo);
 
     queryMetadata.mHostname            = aQuery->mHostname;
+    queryMetadata.mResponseHandler     = aHandler;
+    queryMetadata.mResponseContext     = aContext;
     queryMetadata.mTransmissionTime    = TimerMilli::GetNow() + kResponseTimeout;
     queryMetadata.mSourceAddress       = messageInfo->GetSockAddr();
-    queryMetadata.mDestinationPort     = messageInfo->GetPeerPort();
     queryMetadata.mDestinationAddress  = messageInfo->GetPeerAddr();
+    queryMetadata.mDestinationPort     = messageInfo->GetPeerPort();
     queryMetadata.mRetransmissionCount = 0;
 
     VerifyOrExit((messageCopy = CopyAndEnqueueMessage(*message, queryMetadata)) != nullptr, error = OT_ERROR_NO_BUFS);
@@ -522,6 +500,19 @@ exit:
     }
 }
 
+void Client::QueryMetadata::ReadFrom(const Message &aMessage)
+{
+    uint16_t length = aMessage.GetLength();
+
+    OT_ASSERT(length >= sizeof(*this));
+    aMessage.Read(length - sizeof(*this), sizeof(*this), this);
+}
+
+void Client::QueryMetadata::UpdateIn(Message &aMessage) const
+{
+    aMessage.Write(aMessage.GetLength() - sizeof(*this), sizeof(*this), this);
+}
+
 } // namespace Dns
 } // namespace ot
 
diff --git a/src/core/net/dns_client.hpp b/src/core/net/dns_client.hpp
index 32d38a4d5..045e452ef 100644
--- a/src/core/net/dns_client.hpp
+++ b/src/core/net/dns_client.hpp
@@ -47,78 +47,6 @@
 namespace ot {
 namespace Dns {
 
-/**
- * This class implements metadata required for DNS retransmission.
- *
- */
-class QueryMetadata
-{
-    friend class Client;
-
-public:
-    /**
-     * Default constructor for the object.
-     *
-     */
-    QueryMetadata(void);
-
-    /**
-     * This constructor initializes the object with specific values.
-     *
-     * @param[in]  aHandler  Pointer to a handler function for the response.
-     * @param[in]  aContext  Context for the handler function.
-     *
-     */
-    QueryMetadata(otDnsResponseHandler aHandler, void *aContext);
-
-    /**
-     * This method appends request data to the message.
-     *
-     * @param[in]  aMessage  A reference to the message.
-     *
-     * @retval OT_ERROR_NONE     Successfully appended the bytes.
-     * @retval OT_ERROR_NO_BUFS  Insufficient available buffers to grow the message.
-     *
-     */
-    otError AppendTo(Message &aMessage) const { return aMessage.Append(this, sizeof(*this)); }
-
-    /**
-     * This method reads request data from the message.
-     *
-     * @param[in]  aMessage  A reference to the message.
-     *
-     */
-    void ReadFrom(const Message &aMessage)
-    {
-        uint16_t length = aMessage.Read(aMessage.GetLength() - sizeof(*this), sizeof(*this), this);
-        OT_ASSERT(length == sizeof(*this));
-        OT_UNUSED_VARIABLE(length);
-    }
-
-    /**
-     * This method updates request data in the message.
-     *
-     * @param[in]  aMessage  A reference to the message.
-     *
-     * @returns The number of bytes updated.
-     *
-     */
-    int UpdateIn(Message &aMessage) const
-    {
-        return aMessage.Write(aMessage.GetLength() - sizeof(*this), sizeof(*this), this);
-    }
-
-private:
-    const char *         mHostname;            ///< A hostname to be find.
-    otDnsResponseHandler mResponseHandler;     ///< A function pointer that is called on response reception.
-    void *               mResponseContext;     ///< A pointer to arbitrary context information.
-    TimeMilli            mTransmissionTime;    ///< Time when the timer should shoot for this message.
-    Ip6::Address         mSourceAddress;       ///< IPv6 address of the message source.
-    Ip6::Address         mDestinationAddress;  ///< IPv6 address of the message destination.
-    uint16_t             mDestinationPort;     ///< UDP port of the message destination.
-    uint8_t              mRetransmissionCount; ///< Number of retransmissions.
-};
-
 /**
  * This class implements DNS client.
  *
@@ -193,6 +121,22 @@ private:
         kBufSize = 16
     };
 
+    struct QueryMetadata
+    {
+        otError AppendTo(Message &aMessage) const { return aMessage.Append(this, sizeof(*this)); }
+        void    ReadFrom(const Message &aMessage);
+        void    UpdateIn(Message &aMessage) const;
+
+        const char *         mHostname;
+        otDnsResponseHandler mResponseHandler;
+        void *               mResponseContext;
+        TimeMilli            mTransmissionTime;
+        Ip6::Address         mSourceAddress;
+        Ip6::Address         mDestinationAddress;
+        uint16_t             mDestinationPort;
+        uint8_t              mRetransmissionCount;
+    };
+
     Message *NewMessage(const Header &aHeader);
     Message *CopyAndEnqueueMessage(const Message &aMessage, const QueryMetadata &aQueryMetadata);
     void     DequeueMessage(Message &aMessage);