[Dnsmasq-discuss] Looking up local names doesn't work

Mon May 28 04:15:08 BST 2012

Hello

I'm currently working a DNS server in a local area network. DHCP service is
given by another server which is not under my control. Names on the
internet are working fine, but looking up local names doesn't seem to work.

  IP note hostname  192.168.100.229 DNS LOEA-T7500.ic.sjtu.edu.cn
192.168.100.75 a host LOEA-VM004.ic.sjtu.edu.cn  192.168.100.31 a host
LOEA-VM002.ic.sjtu.edu.cn  192.168.100.201 DHCP  202.120.2.101 upstream DNS
202.112.26.34 upstream DNS

I use "dig" on LOEA-VM004 to see if I can get LOEA-VM002 resolved via dns,
but there is no answer:

[ian at LOEA-VM004 ~]$ dig LOEA-VM002
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5 <<>> LOEA-VM002
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 38313
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;LOEA-VM002.INA

;; AUTHORITY SECTION:
.10402INSOAa.root-servers.net. nstld.verisign-grs.com. 2012052601 1800 900
604800 86400

;; Query time: 2 msec
;; SERVER: 192.168.100.229#53(192.168.100.229)
;; WHEN: Mon May 28 10:08:31 2012
;; MSG SIZE  rcvd: 103

At the same time, I use tcpdump to listen on DNS server

[root at LOEA-T7500 ian]# tcpdump \(host 192.168.100.229 and port and port
53\) or \(host 192.168.100.201\) -nnvv
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96
bytes
10:07:23.390606 IP (tos 0x0, ttl  64, id 31380, offset 0, flags [none],
proto: UDP (17), length: 56) 192.168.100.75.36380 > 192.168.100.229.53:
[udp sum ok]  38313+ A? LOEA-VM002. (28)
10:07:23.390765 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto:
UDP (17), length: 56) 192.168.100.229.34909 > 192.168.100.201.53: [bad udp
cksum 14c2!]  51850+ A? LOEA-VM002. (28)
10:07:23.390771 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto:
UDP (17), length: 56) 192.168.100.229.34909 > 202.112.26.34.53: [bad udp
cksum d343!]  51850+ A? LOEA-VM002. (28)
10:07:23.390774 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto:
UDP (17), length: 56) 192.168.100.229.34909 > 202.120.2.101.53: [bad udp
cksum 3d73!]  51850+ A? LOEA-VM002. (28)
10:07:23.390962 IP (tos 0x0, ttl  64, id 22929, offset 0, flags [none],
proto: ICMP (1), length: 84) 192.168.100.201 > 192.168.100.229: ICMP
192.168.100.201 udp port 53 unreachable, length 64
IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto: UDP (17), length:
56) 192.168.100.229.34909 > 192.168.100.201.53:  51850+[|domain]
10:07:23.391730 IP (tos 0x0, ttl  59, id 6539, offset 0, flags [none],
proto: UDP (17), length: 131) 202.112.26.34.53 > 192.168.100.229.34909:
 51850 NXDomain q: A? LOEA-VM002. 0/1/0 ns: . SOA[|domain]
10:07:23.391772 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto:
UDP (17), length: 131) 192.168.100.229.53 > 192.168.100.75.36380:  38313
NXDomain q: A? LOEA-VM002. 0/1/0 ns: . SOA[|domain]
10:07:23.391967 IP (tos 0x0, ttl  59, id 32177, offset 0, flags [none],
proto: UDP (17), length: 131) 202.120.2.101.53 > 192.168.100.229.34909:
 51850 NXDomain q: A? LOEA-VM002. 0/1/0 ns: . SOA[|domain]

Here is /etc/hosts /etc/dnsmasq.conf /etc/resolv.dnsmasq.conf
and /etc/resolv.conf on LOEA-T7500

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost
#127.0.0.1 LOEA-T7500.ic.sjtu.edu.cn LOEA-T7500
::1 localhost6.localdomain6 localhost6
127.0.0.1 LOEA-T7500 # added by Apache Friends XAMPP

resolv-file=/etc/resolv.dnsmasq.conf
expand-hosts
domain=ic.sjtu.edu.cn
conf-dir=/etc/dnsmasq.d

search ic.sjtu.edu.cn
domain ic.sjtu.edu.cn
nameserver 192.168.100.201
nameserver 202.112.26.34
nameserver 202.120.2.101

; generated by /sbin/dhclient-script
search ic.sjtu.edu.cn
nameserver 127.0.0.1
;nameserver 192.168.100.201
;nameserver 202.112.26.34
;nameserver 202.120.2.101

I ping LOEA-T7500 on LOEA-VM004, it is resolved as 127.0.0.1.
And here is the ip-hostname list on DHCP, I mean those hosts do send their
hostnames to DHCP when asking for a lease.

192.168.100.31  - 255.255.255.0  - ea-b3-8d-73-71-65   -2012/5/28 15:07:09
    -D-  LOEA-VM002.ic.sjtu.edu.cn
192.168.100.75  - 255.255.255.0  - 06-96-c1-4f-04-43   -2012/5/28 16:05:50
    -D-  LOEA-VM004.ic.sjtu.edu.cn

How can I solve this problem? Thank you.

-- 
Huangtian
Shanghai Jiao Tong University
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/attachments/20120528/4d37eac1/attachment.html>