Why name resolution commands (host & ping) timeouts and does not respond to dns query, but tcpdump shows the dns query response recieved instantly ?
Issue
- Connection timeout is observed for host & ping commands.
# host XYZ
;; connection timed out; no servers could be reached
- But tcpdump does shows response packets received for name resolution query.
13:56:32.426659 XX:YY:4b:a7:34:30 > XX:YY:d7:72:e9:50, ethertype IPv4 (0x0800), length 76: (tos 0x0, ttl 64, id 63692, offset 0, flags [none], proto: UDP (17), length: 62) XX.YY.BB.CC.49932 > VV.DD.BB.CC.domain: [bad udp cksum a35a!] 3209+ A? xyz.abc.com. (34)
13:56:32.428442 XX:YY:d7:72:e9:50 > aa:bb:0b:61:c2:0c, ethertype IPv4 (0x0800), length 116: (tos 0x0, ttl 62, id 51464, offset 0, flags [none], proto: UDP (17), length: 102) VV.DD.BB.CC.domain > XX.YY.BB.CC.49932: [udp sum ok] 3209* q: A? xyz.abc.com. 2/0/0 xyz.abc.com. CNAME spsc0007d.abc.com., spsc0007d.abc.com. A KK.JJ.BB.CC (74)
13:56:37.428130 XX:YY:4b:a7:34:30 > XX:YY:d7:72:e9:50, ethertype IPv4 (0x0800), length 76: (tos 0x0, ttl 64, id 63693, offset 0, flags [none], proto: UDP (17), length: 62) XX.YY.BB.CC.49932 > VV.DD.BB.CC.domain: [bad udp cksum a35a!] 3209+ A? xyz.abc.com. (34)
13:56:37.429842 XX:YY:d7:72:e9:50 > aa:bb:0b:61:c2:0c, ethertype IPv4 (0x0800), length 116: (tos 0x0, ttl 62, id 51465, offset 0, flags [none], proto: UDP (17), length: 102) VV.DD.BB.CC.domain > XX.YY.BB.CC.49932: [udp sum ok] 3209* q: A? xyz.abc.com. 2/0/0 xyz.abc.com. CNAME spsc0007d.abc.com., spsc0007d.abc.com. A KK.JJ.BB.CC (74)
13:56:42.935447 XX:YY:d7:72:e9:50 > CC:NN:0b:8e:c3:1c, ethertype IPv4 (0x0800), length 153: (tos 0x0, ttl 62, id 10718, offset 0, flags [none], proto: UDP (17), length: 139) VV.DD.BB.CC.domain > 10.255.154.20.58794: [udp sum ok] 11733* q: AAAA? pmtpw02.abc.com. 0/1/0 ns: abc.com. SOA ayz.abs.com. net.abs.com. 2838379 10800 3600 2592000 600 (111)
Environment
- Red Hat Enterprise Linux (All releases)
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