ESXi5 NTP not syncing, configuration issue?

I configured NTP to sycn against a local server, tcpdump shows req and reply from the NTP server

tcpdump-uw: listening on vmk0, link-type EN10MB (Ethernet), capture size 96 bytes
03:52:36.296738 IP (tos 0xc0, ttl 64, id 11220, offset 0, flags [none], proto UDP (17), length 76)
    10.100.110.104.123 > 10.100.110.83.123: [bad udp cksum 71be!] NTPv4, length 48
        Client, Leap indicator: clock unsynchronized (192), Stratum 0, poll 6s, precision -20
        Root Delay: 0.000000, Root dispersion: 0.000000, Reference-ID: (unspec)
          Reference Timestamp:  0.000000000
          Originator Timestamp: 0.000000000
          Receive Timestamp:    0.000000000
          Transmit Timestamp:   3316391556.296519286 (2005/02/03 03:52:36)
            Originator - Receive Timestamp:  0.000000000
            Originator - Transmit Timestamp: 3316391556.296519286 (2005/02/03 03:52:36)
03:52:36.297376 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 76)
    10.100.110.83.123 > 10.100.110.104.123: [udp sum ok] NTPv4, length 48
        Server, Leap indicator:  (0), Stratum 3, poll 6s, precision -20
        Root Delay: 0.060379, Root dispersion: 0.031723, Reference-ID: 10.1.100.250
          Reference Timestamp:  3557063872.835467905 (2012/09/19 17:17:52)
          Originator Timestamp: 3316391556.296519286 (2005/02/03 03:52:36)
          Receive Timestamp:    3557064449.635109943 (2012/09/19 17:27:29)
          Transmit Timestamp:   3557064449.635128945 (2012/09/19 17:27:29)
            Originator - Receive Timestamp:  +240672893.338590651
            Originator - Transmit Timestamp: +240672893.338609665
tcpdump-uw: pcap_loop: recvfrom: Interrupted system call

But no sync on ESXi side, /var/log/syslog.log shows no sync

2005-02-03T03:52:35Z root: ntpd Starting ntpd
2005-02-03T03:52:35Z ntpd[7476]: ntpd 4.2.6p2@1.2194-o Tue Mar 15 09:36:00 UTC 2011 (1)
2005-02-03T03:52:35Z ntpd[7477]: proto: precision = 0.815 usec
2005-02-03T03:52:35Z ntpd[7477]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen and drop on 1 v6wildcard :: UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen normally on 2 lo0 127.0.0.1 UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen normally on 3 vmk0 10.100.110.104 UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen normally on 4 lo0 ::1 UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen normally on 5 lo0 fe80::1 UDP 123
2005-02-03T03:52:35Z ntpd[7477]: Listen normally on 6 vmk0 fe80::200:50ff:fea4:5faa UDP 123