Newbie : Testing a port using Portqry.exe and Wireshark

Hello All,

I am a newbie in networking and wireshark.

To test a port, I am using portqry.exe on a sender server and capturing packets on the receving PC.

Please advise if my suspicion of a network issue is reasonable. Thanks.

• portqry.exe -n 10.20.30.40 -e 68 -p udp -sp 4011 - I understand portqry sends a dummy packet to host (-n) at port (-e) from port(-sp) using protocol (-p) - 10.20.30.40 is a random PC in some other Adsite
• Wireshark captures packets at 10.20.30.40; no capture filters set

• when portqry.exe executed from : (a) W2K8 WDS server (boot image server) : No packets were received by 10.20.30.40 (b) a random XP PC in same subnet of WDS server : No packets were received by 10.20.30.40 (c) a random WDS W2K8 server from ANOTHER Adsite : UDP Packet received fine.

• If I change the portqry.exe protocol from udp to tcp, then packet is received fine from all WDS/XP/Server above.

• Windows Firewall on W2K8 servers is disabled.
• HP Switches

Based on the above, can I conclude that UDP packets that originate from the first Adsite with source port as 4011 do not reach their destination due to a network issue?