CODEWITHSUNDEEP
linuxdns
Ankur Jain
Ankur Jain

Reputation: 164

host command not resolving reverse lookup zone using secondary dns entry

I am using two dns entries 

nameserver x.x.x.x
nameserver y.y.y.y

where x.x.x.x is ip for domain1 and y.y.y.y is ip for domain2

i am using host command for reverse lookup.

host domain1 gives 2 ip's a and b 
host domain2 gives 2 ip's c and d

now when i do

host a

it gives me reverse lookup but

host c

doesnot .

Does host command reverse lookup works only with primary DNS and not with Secondary DNS. I have taken wireshark captures and seen no request is going to secondary dns for failed case.

Whatever i have read about it /etc/resolver works in the following way:

You should have all the DC's which you want to resolve be resolvable using primary dns and forwarders in it. From DNS you can get two types of errors NXDOMAIN Timeout NXDOMAIN is when your dns authoritatively says that i cannot find this domain and then it does not searches further. When you get timeout from primary dns resolver then continue and tries to resolve using secondary dns.

Upvotes: 1

Views: 2870

Answers (1)

Celada
Celada

Reputation: 22261

The order in which nameservers specified in /etc/resolv.conf are used is undefined. Usually the first one will be used first and subsequent ones will be used if the previous ones fail to respond, but you can't count on that.

In any case, each of the resolvers you list in /etc/resolv.conf should have the same view of DNS and should produce the same answer to a given question.

If your resolvers are only able to resolve some domains and not others, you should fix that problem.

Upvotes: 1

Related Questions