ip addresses

My router configured by ISP tech and it is set to get DNS server address automatically from upstream. Is there is a way to find out the IP address of the dns server used by my router which is located at Is there Linux, Unix, Apple OS X, or MS-Windows command that I can use get the same information?


How can I look up IP addresses under UNIX or Linux operating systems using command line options?

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Q. I’m running Apache 2 server under FreeBSD jail. However, I see lots of warning / error messages in /var/log/httpd-error.log as follows:

[Sat Sep 20 20:47:09 2008] [warn] (61)Connection refused: connect to listener on
[Sat Sep 20 20:47:10 2008] [warn] (61)Connection refused: connect to listener on
[Sat Sep 20 20:47:11 2008] [warn] (61)Connection refused: connect to listener on

How do stop all these warning messages flooding my Apache log files?


Can you explain DNS name resolution concept? Why I need to set DNS resolution for my Windows or Linux server? How do I setup DNS name resolution under Linux / UNIX server system?


Can one Linux / BSD system respond to multiple IP address on a single Ethernet interface? I need to run multiple web sites and mod_ssl with a single server. How do I configure my box for multiple IP address?

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Q. I’m experiencing decreased network performance due to ARP broadcasts coming from one system. What would cause a lot of ARP broadcasts from one server / computer?


Q. How do I configure my Postfix mail server to scan incoming mail for spam using DNS Blackhole List such as: a) The Spamhaus b) Open Relay Database etc A. To discard spam or garbage email you can use 3rd party services such as Spamhaus. These are realtime database of IP addresses of verified spam […]