draft

Author: Deland-Han

support/windows-server/active-directory/domain-join-error-0x40-the-specified-network-name-is-no-longer-available.md

@@ -39,7 +39,7 @@ NetpJoinDomainOnDs: Function exits with status of: 0x40
 This issue occurs when either of the following conditions is met:
 
 - A WAN accelerator device responds to acknowledge the TGS request package, but the response does not arrives at the Key Distribution Center (KDC). Generally, IP Time to Live (TTL) frame fields have values of 64 or lower because this is the TTL used by Unix-like devices, and WAN accelerators are generally based on Linux.
-- A network device such as a firewall between the client and the DC dropped the KDC response. You can find more details in the concurrent network trace of the DC traffic.
+- A network device such as a firewall between the client and the Domain Controller (DC) dropped the KDC response. You can find more details in the concurrent network trace of the DC traffic.
 
 ## Troubleshooting
 
@@ -79,4 +79,25 @@ Here's an example of a network trace:
 1564 DC1.ADATUM.COM         CLIENT1  TCP        TCP:Flags=...A.R.., SrcPort=Kerberos(88), DstPort=59259, PayloadLen=0, Seq=2785284136, Ack=1299632507, Win=0 (scale factor 0x0) = 0           {TCP:267, IPv4:5}
 ```
 
+Here is the analysis of the network traffic:
+
+> [!NOTE]
+> A full understanding of the behavior needs a trace from the DC network, it may also clarify why the client does not reset the session earlier. The following is what we can tell about the failure:
+
+In frames 1541, 1542 and 1545 the client first retransmits the TCP segment and then lowers the size of the frame. The data in frame 1545 is acknowledged in frame 1546.
+
+The client continues to send data until the last segment in 1550 with Push bit and last byte 1299631114. This is acknowledged by the server in frame 1555.
+
+In the meantime, the client sends another request to the serve in frames 1552 and 1556, last byte 1299632506. This is acknowledged by the server in frame 1558.
+
+But until the client decides to terminate the session, there is just a single message from the server (frame 1553). The sequence number that make it to the client indicate the server does send other data, from the sequence numbers:
+
+```output
+2785282676 first in frame 1540
+2785284426 first in frame 1555
+2785284136 first in frame 1563
+```
+
+The last sequence number is lower than the one the server sends in frame 1555. The client never saw this data and thus acknowledges 2785282676 throughout the network trace. This is a direct indication of problems with the correct flow of network traffic.
+
 From the trace, you can find the DC doesn't respond to the Ticket Granting Service (TGS) request from the client for the Service Principal Name (SPN) `CIFS/DC1.ADATUM.COM`. It sends back a TCP acknowledgment, which suggests the DC received the TGS request. However, it doesn't reply with a valid TGS response. Finally, the client terminates the TCP connection.