Sunday, May 6, 2012

Using nslookup to help diagnose DNS resolving issue

If you are having issues to resolve your servers to the designated name servers, you may want to use these 3 tools (nslookup, dig, host) which can help to diagnose the DNS resolution. This entry mentions only nslookup.

Utility 1: nslookup
nslookup is one useful tools to assist in diagnosing problems with your resolving. Unfortunately, this niffy tools is already deprecated or in other words not actively maintained.

# nslookup -debug
(-debug =  Turn on or off the display of the full response packet and any intermediate response packets when searching.)

# nslookup -debug -d2
(-d2 = Turn debugging mode on or off. This displays more about what nslookup is doing.)

Sample output on d2
lock_lookup dighost.c:3173
main parsing
looking up
ndots is 1.
freeing commctx
freeing socketmgr
freeing timermgr
destroy DST lib
detach from entropy
unlock_lookup dighost.c:3219

  1. Tracking "Server Failed" Error from DNS

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