In Apex, what is the difference between a completed and dropped request?

Dropped requests are referring to a application request or a 3-way handshake request like a SYN but not response?

• This number indicates that Trending saw request packets but no reply packet.
• This number should be 0 unless something upstream dropped a packet.

Customer is asking how to see the following in APEX:

1. TCP SYNs being sent from one system to another without a TCP SYN response ( the three way handshake ).
2. TCP RESETs being sent in response to a connection attempt.   Perhaps in response to #1 above.

Dropped Requests has nothing to do with incomplete handshakes.

Your request is a datapoint that we do not track today as a KPI (Connections Failed To Establish); however, this is part of EUE scoring.

There are 2 scenarios:

• SYN’s Sent but no reply
• SYN’s Sent, SYN ACK sent, Connection Not Established (either by RST or by client giving up)

Scenario 1 – SYN’s Sent but no Reply

This is attributed to the Server, such as the service isn’t running or a firewall (either on the server or on the network) is preventing reply packets, but Observer never sees the reply packets.

Unresponsive server during connection setup

Scenario 2 – Server is replying but connection is not being established. This will be attributed to the network dropping packets

Packet loss and retransmissions are preventing connection setup

Ignore the duplicate packets. This is a SPAN issue.