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Comments (8)

Abderahim commented Mar 3 2017 Comment Permalink

Hello Chris,

I have experienced some issues with LDAP client (OpenLDAP). It does not switch between DNS entires defined on /etc/recsolv.conf if we don't add nsorder (nsorder:local,bind4) entry on ldap.conf.

This is very helpful if Applications users (Oracle, ...) are defined on LDAP side, otherwise, if there a problem on the first DNS, Ldap client don't switch to second DNS.

Good post.

Best regards,
Abderahim

GEK7_Richard_Fowler commented May 9 2015 Comment Permalink

Hello, have tried several times to get nslookup command to try next name server if it fails on first nameserver. have opened a call with support and there answer was it did not fail. first nameserver gave a response that i could not find the address. Do i have to turn my server into a DNS server for this to work? my config and output [ri3pa440:rfowler:/etc]sudo cat /etc/resolv.conf nameserver 146.89.3.68 nameserver 146.89.3.69 nameserver 172.20.179.225 domain msd.ihost.com options rotate [ri3pa440:rfowler:/etc]nslookup smtp.ppdi.com Server: 146.89.3.68 Address: 146.89.3.68#53 ** server can't find smtp.ppdi.com.msd.ihost.com: NXDOMAIN [ri3pa440:rfowler:/etc]nslookup smtp.ppdi.com 172.20.179.225 Server: 172.20.179.225 Address: 172.20.179.225#53 Non-authoritative answer: Name: smtp.ppdi.com Address: 172.17.181.245 thank you. richard fowler

Mrtyldrm commented Mar 10 2015 Comment Permalink

Hi Chris, If I lose all of my dns servers which specified on /etc/resolv.conf , Can I reach to a host which it's dns definitions has already on the cache before lost the dns servers. I start the netcd and ping serverA. Check the caching out and see its definitions on there. After remove all dns servers from /etc/resolv.conf and try to ping serverA again but it failed with "host not found message." So can we say the dns caching is useful only when dns servers is up? If no, there is a caching dns option for if all dns servers down

cggibbo commented Feb 7 2013 Comment Permalink

"...under DNS 4.9 or DNS 8, you can replace domain nsr.hp.com with search nsr.hp.com hp.com and get the same functionality." http://www.diablotin.com/librairie/networking/dnsbind/ch06_01.htm

JMRoderick commented Feb 6 2013 Comment Permalink

Chris, There's some debate here about the use of domain when search is specified, e.g domain biz.co.uk nameserver 1.2.3.4 nameserver 2.3.4.5 nameserver 3.4.5.6 search biz.co.uk shop.biz.co.uk Documentation says domain and search are mutually exclusive and the last entry wins out BUT it's not completely clear on whether domain can be left out if search is populated (as above). What do you think?

cggibbo commented Nov 5 2012 Comment Permalink

Hi nmistryLH, FYI. There are new options for /etc/resolv.conf in AIX 7.1/6.1 (not in 5.3): timeout: Enables you to specify the initial timeout for a query to a nameserver. The default value is five seconds. The maximum value is 30 seconds. For the second and successive rounds of queries, the resolver doubles the initial timeout and is divided by the number of nameservers in the resolv.conf file. attempts: Enables you to specify how many queries the resolver should send to each nameserver in the resolv.conf file before it stops execution. The default value is 2. The maximum value is 5. rotate: Enables the resolver to use all the nameservers in the resolv.conf file, not just the first one. The resolv.conf file can contain a maximum of three nameserver entries, and any number of options entries. HTH. Chris

nmistryLH commented Nov 3 2012 Comment Permalink

I have some AIX and DNS related questions based on some recent troubles with a system. We have a p570 with AIX 5.3 that runs oracle 11g. Recently there were some communication issues between DB and App server and it was pointed out it had something to do with DNS. My question is how does AIX handle DNS requests? Does it automatically fail to secondary if primary is not available? Does it go back to primary automatically when its back online? Can we point to more than two DNS servers? Thanks

DerekKeightley commented Nov 23 2011 Comment Permalink

Great post Chris, good to know about the netcd daemon, I have previously used open source options.