Name Resolution Issue from Browser only, on Debian 5.0.4
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From: Hemanth M. C. on 23 Feb 2010 03:40 Hi All, I am facing a rather peculiar issue. I installed Debian 5.0.4 on my laptop. The basic network connectivity works fine, and the DHCP client daemon seems to have picked up the right config info from my DSL router. But, anything related to HTTP does not work - browser, WGET, etc. This is what my output looks like: ---------------------------------------------------------------------- hchandra(a)hchandra-lap:~$ cat /etc/resolv.conf ### BEGIN INFO # # Modified_by: NetworkManager # Process: /usr/bin/NetworkManager # Process_id: 2988 # ### END INFO nameserver 192.168.1.1 nameserver 192.168.1.1 hchandra(a)hchandra-lap:~$ ping ftp.debian.org PING ftp.debian.org (130.89.149.226) 56(84) bytes of data. 64 bytes from ftp.debian.org (130.89.149.226): icmp_seq=1 ttl=50 time=213 ms 64 bytes from ftp.debian.org (130.89.149.226): icmp_seq=2 ttl=50 time=213 ms 64 bytes from ftp.debian.org (130.89.149.226): icmp_seq=3 ttl=50 time=212 ms ^C --- ftp.debian.org ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2002ms rtt min/avg/max/mdev = 212.532/213.114/213.558/0.430 ms hchandra(a)hchandra-lap:~$ ftp ftp.debian.org Connected to ftp.debian.org. 220 ftp.debian.org FTP server Name (ftp.debian.org:hchandra): anonymous 331 Please specify the password. Password: 230 Login successful. Remote system type is UNIX. Using binary mode to transfer files. ftp> bye 221 Goodbye. hchandra(a)hchandra-lap:~$ wget http://www.debian.org --2010-02-20 17:38:08-- http://www.debian.org/ Resolving www.debian.org... 1.0.0.0 Connecting to www.debian.org|1.0.0.0|:80... ^C hchandra(a)hchandra-lap:~$ wget --no-dns-cache http://www.debian.org/ --2010-02-20 17:43:26-- http://www.debian.org/ Resolving www.debian.org... 1.0.0.0 Connecting to www.debian.org|1.0.0.0|:80... ^C hchandra(a)hchandra-lap:~$ ---------------------------------------------------------------------- >From this, it should be obvious that ping & ftp are able to resolve the DNS names correctly, but WGET and any browser resolve it to '1.0.0.0'. Can anyone tell me what the problem could be? What is the difference between the way ping & ftp resolve names and the way wget and browsers do so? Regards, Hemanth -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/502642.23771.qm(a)web112510.mail.gq1.yahoo.com
From: Camaleón on 23 Feb 2010 11:10 On Tue, 23 Feb 2010 00:30:15 -0800, Hemanth M. C. wrote: > I am facing a rather peculiar issue. I installed Debian 5.0.4 on my > laptop. The basic network connectivity works fine, and the DHCP client > daemon seems to have picked up the right config info from my DSL router. > But, anything related to HTTP does not work - browser, WGET, etc. Does this help? WGET can't resolve host http://serverfault.com/questions/76421/wget-cant-resolve-host Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/pan.2010.02.23.16.00.51(a)gmail.com
From: Hemanth M. C. on 23 Feb 2010 23:00 Camaleón, Thank you for replying to my mail. My replies inline... On Tue, February 23, 2010 21:30:51 +0530, Camaleón wrote: > >On Tue, 23 Feb 2010 00:30:15 -0800, Hemanth M. C. wrote: > >> I am facing a rather peculiar issue. I installed Debian 5.0.4 on my >> laptop. The basic network connectivity works fine, and the DHCP client >> daemon seems to have picked up the right config info from my DSL router. >> But, anything related to HTTP does not work - browser, WGET, etc. > >Does this help? > >WGET canât resolve host >http://serverfault..com/questions/76421/wget-cant-resolve-host The solution mentioned in the link does not work for me, since my installation is a new installation - I did not touch the nsswitch.conf file. However, the answer seems to lie somewhere there. I played around with the nsswitch.conf file, but was unable to make it resolve correctly. This is the file: -------------------------------------------------------------------------------- # /etc/nsswitch..conf # # Example configuration of GNU Name Service Switch functionality. # If you have the `glibc-doc-reference' and `info' packages installed, try: # `info libc "Name Service Switch"' for information about this file.. passwd: compat group: compat shadow: compat hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4 networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis -------------------------------------------------------------------------------- I learnt a lot about this file from the man pages, but was unable to figure out what mdns4 and mdns4_minimal are. I will try to play around with this for some more time, but would appreciate any input on this issue from anybody. Meanwhile, I got some more details on the quirky behaviour: -------------------------------------------------------------------------------- hchandra(a)hchandra-lap:~$ wget http://www.ibm.com/ --2010-02-24 08:48:43-- http://www.ibm.com/ Resolving www.ibm.com... 1.0.0.0 Connecting to www.ibm.com|1.0.0.0|:80... ^C hchandra(a)hchandra-lap:~$ getent hosts www.ibm.com 1.0.0.0 www.ibm.com hchandra(a)hchandra-lap:~$ ping www.ibm.com PING www.ibm.com.cs186.net (129.42.56.216) 56(84) bytes of data. ^C --- www.ibm.com.cs186.net ping statistics --- 2 packets transmitted, 0 received, 100% packet loss, time 1013ms hchandra(a)hchandra-lap:~$ getent hosts www.ibm.com 129.42.56.216 www.ibm.com hchandra(a)hchandra-lap:~$ wget http://www.ibm.com/ --2010-02-24 08:49:19-- http://www.ibm.com/ Resolving www.ibm.com... 129.42.56.216 Connecting to www.ibm.com|129.42.56.216|:80... connected. HTTP request sent, awaiting response... 302 Found Location: http://www.ibm.com/in/ [following] --2010-02-24 08:49:20-- http://www.ibm.com/in/ Reusing existing connection to www.ibm.com:80. HTTP request sent, awaiting response... 301 Moved Permanently Location: http://www.ibm.com/in/en/ [following] --2010-02-24 08:49:20-- http://www.ibm.com/in/en/ Reusing existing connection to www.ibm.com:80. HTTP request sent, awaiting response... 200 OK Length: 31696 (31K) [text/html] Saving to: `index.html.2' 100%[======================================>] 31,696 46.1K/s in 0.7s 2010-02-24 08:49:22 (46.1 KB/s) - `index.html.2' saved [31696/31696] -------------------------------------------------------------------------------- In short, pinging a certain destination helps the getent and wget commands resolve the name correctly. Why is this so? Are the DNS lookups cached somewhere? Does this cache have to be cleared? Thank you, Regards, Hemanth -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/71826.14560.qm(a)web112514.mail.gq1.yahoo.com
From: Celejar on 23 Feb 2010 23:50 On Tue, 23 Feb 2010 19:58:07 -0800 (PST) "Hemanth M. C." <mchemanth(a)yahoo.com> wrote: .... > In short, pinging a certain destination helps the getent and wget commands resolve the name correctly. Why is this so? Are the DNS lookups cached somewhere? Does this cache have to be cleared? I don't know the solution to your overall problem, but IIUC, DNS results are not cached by a basic linux system, unless you're running a caching DNS application, such as dnsmasq. To see if caching is happening, one runs 'dig some_site' twice in a row. If caching is happening, the second "Query time:" should be 0, while the first will be some number of milliseconds (unless, of course, the domain is already in the cache). Without caching, all queries should have a non-zero query time. Of course, there could be caching taking place somewhere upstream of your box. Celejar -- foffl.sourceforge.net - Feeds OFFLine, an offline RSS/Atom aggregator mailmin.sourceforge.net - remote access via secure (OpenPGP) email ssuds.sourceforge.net - A Simple Sudoku Solver and Generator -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/20100223234011.54301823.celejar(a)gmail.com
From: Camaleón on 24 Feb 2010 03:40
On Tue, 23 Feb 2010 19:58:07 -0800, Hemanth M. C. wrote: > On Tue, February 23, 2010 21:30:51 +0530, Camaleón wrote: > > >>Does this help? >> >>WGET can't resolve host >>http://serverfault.com/questions/76421/wget-cant-resolve-host > > The solution mentioned in the link does not work for me, since my > installation is a new installation - I did not touch the nsswitch.conf > file. However, the answer seems to lie somewhere there. I played around > with the nsswitch.conf file, but was unable to make it resolve > correctly. This is the file: (...) -------------------------------------------------------------------------------- > # /etc/nsswitch.conf > > hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4 -------------------------------------------------------------------------------- > I learnt a lot about this file from the man pages, but was unable to > figure out what mdns4 and mdns4_minimal are. I will try to play around > with this for some more time, but would appreciate any input on this > issue from anybody. In fact, it seems those values are the cause of some resolution slowness: *** mdns listed in nsswitch.conf causes excessive time for dns lookups https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/94940 *** You can try the suggested steps, just to check if the situation improves. (...) > In short, pinging a certain destination helps the getent and wget > commands resolve the name correctly. Why is this so? Are the DNS lookups > cached somewhere? Does this cache have to be cleared? As you are using the router's DNS facility, is up to the device performing such operation. Another thing you can try is by using your ISP's own DNS servers, instead the router's ones and see if you get different results. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/pan.2010.02.24.08.29.48(a)gmail.com |