Revers DNS lookup

[Sergejs Svitnevs]

Hello

Our app server tries to reverse lookup the connection query to find out the server name and all requests to that server are delayed by 10-15 sec.

Unfortunately, I can not change outdated reverse lookup records in DNS and can not disable reverse dns lookup for my app. Is it possible to manage private Reverse IP lookups through files contained simple list of computer names and associated static IP?

Thanks

[Alex Lavrov.]

Yep,

just populate your /etc/hosts file with the entries and make sure that in /etc/nsswitch.conf in hosts line files comes first.

This way it will first check in files and it will be very fast.

Alex.

[Muthukumar_5]

Basic setup to use /etc/hosts file with hosts: entry setting in /etc/nsswitch.conf.

Change hosts: entry as,

-- /etc/nsswitch.conf --
hosts: files

-- /etc/hosts
127.0.0.1 localhost loopback
ip-address fqdn hostname

It will do your need. Just copy this /etc/hosts file setting to all available machines in the network.

Check routing entry for this also If machine is not reachable.
# netstat -rn

hth.

[Arunvijai_4]

Edit your /etc/hosts and add your static IPs there. It should do.

-Arun

[njia_1]

Hi

I had this problem as well, adding hostname to /etc/hosts is not a good solution because the ip address and hostname are keeping changing. New hosts could be added to the network everyday.

[Sergejs Svitnevs]

From my point of view I can use /etc/hosts file for Forward DNS lookup (hostname->IP)only.
Reverse IP address lookup converts the IP to the name and '/etc/hosts' file does not support this future.

[Muthukumar_5 · Accepted solution]

/etc/hosts will be able to reverse lookup too. (ip-address --> hostname)

--- /etc/hosts ---
127.0.0.1 localhost loopback

# nslookup 127.0.0.1
Using /etc/hosts on: hostname

looking up FILES
Name: localhost
Address: 127.0.0.1
Aliases: loopback

It will return localhost and loopback there on configuring hosts: files there.

It is showing that it is doing R-Lookup too.

hth.

[Alex Lavrov.]

It does.

host->ip and ip->host, works both with /etc/hosts.

Alex.

[Sergejs Svitnevs]

Thanks