Why isn't my localhost resolved to 127.0.0.1

Question

Level 1

8 points

Why isn't my localhost resolved to 127.0.0.1

One of my application cannot work properly due to the localhost is unreachable. I tried to figure out what the problem is and I found out that the localhost is not 127.0.0.1.

The following is the output message when I run "dig localhost"

MarydeMacBook-Air:resolver feng$ ping localhost

PING localhost.local (202.102.110.203): 56 data bytes

Request timeout for icmp_seq 0

^C

--- localhost.local ping statistics ---

2 packets transmitted, 0 packets received, 100.0% packet loss

MarydeMacBook-Air:resolver feng$ dig localhost

; <<>> DiG 9.8.3-P1 <<>> localhost

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53519

;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:

;localhost. IN A

;; ANSWER SECTION:

localhost. 35 IN A 202.102.110.203

;; Query time: 9 msec

;; SERVER: 192.168.0.1#53(192.168.0.1)

;; WHEN: Wed Jul 1 07:55:37 2015

;; MSG SIZE rcvd: 43

The localhost is resolved to a foreign IP, 202.102.110.203, and the DNS server is 192.168.0.1 which is my wifi switch address.

The output of command "nslookup localhost" confirmed that:

MarydeMacBook-Air:resolver feng$ nslookup localhost

Server: 192.168.0.1

Address: 192.168.0.1#53

Non-authoritative answer:

Name: localhost.local

Address: 202.102.110.203

Does anyone knows what's the matter and how to resolve this problem?

Many thanks!

MacBook Air, OS X Yosemite (10.10.4)

Posted on Jun 30, 2015 5:00 PM

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Answer 1

Linc Davis

Level 10

209,739 points

Jun 30, 2015 5:09 PM in response to Thomas Qiu

What are the contents of /etc/hosts ?

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Answer 2

Thomas Qiu Author

Level 1

8 points

Jun 30, 2015 6:30 PM in response to Linc Davis

I Have checked /etc/hosts and there is a record of localhost. The content is something like the below.

127.0.0.1. localhost

So it isn't the problem about local hosts configuration.

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Answer 3

Linc Davis

Level 10

209,739 points

Jun 30, 2015 6:39 PM in response to Thomas Qiu

You're resolving "localhost.local", not literally localhost. Apparently your DNS server has a record pointing to it.

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Answer 4

Thomas Qiu Author

Level 1

8 points

Jul 1, 2015 1:36 AM in response to Linc Davis

I added localhost.local in /etc/hosts. But it doesn't work either.

Here's the content of this file:

MarydeMacBook-Air:etc feng$ cat /etc/hosts

##

# Host Database

#

# localhost is used to configure the loopback interface

# when the system is booting. Do not change this entry.

##

127.0.0.1 localhost localhost.local

255.255.255.255 broadcasthost

::1 localhost

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Answer 5

Linc Davis

Level 10

209,739 points

Jul 1, 2015 6:57 AM in response to Thomas Qiu

The local TLD is reserved for Bonjour. The hosts file is for pre-empting unicast name resolution.

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Answer 6

Thomas Qiu Author

Level 1

8 points

Jul 1, 2015 7:21 AM in response to Linc Davis

Could you please tell me how I can fix this problem?

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Answer 7

Linc Davis

Level 10

209,739 points

Jul 1, 2015 7:43 AM in response to Thomas Qiu

Maybe I could make a suggestion, if I knew what the problem was. What are you trying to accomplish?

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Answer 8

Thomas Qiu Author

Level 1

8 points

Jul 1, 2015 7:52 AM in response to Linc Davis

Right now I cannot connect localhost properly. But I can connect 127.0.0.1 correctly. This problem makes tomcat, mysql and some IDE works abnormally.

I'm in China. It seems that ISP's DNS server should not have the record for localhost.

Do you have any idea to find out the cause?

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Answer 9

Linc Davis

Level 10

209,739 points

Jul 1, 2015 7:59 AM in response to Thomas Qiu

Rename whatever it is that has the conflicting name "localhost.local", or remove the invalid record from your DNS.

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Answer 10

Thomas Qiu Author

Level 1

8 points

Jul 1, 2015 8:09 AM in response to Linc Davis

MarydeMacBook-Air:resolver feng$ dig localhost

; <<>> DiG 9.8.3-P1 <<>> localhost

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10061

;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:

;localhost. IN A

;; ANSWER SECTION:

localhost. 35 IN A 202.102.110.203

;; Query time: 8 msec

;; SERVER: 192.168.0.1#53(192.168.0.1)

;; WHEN: Wed Jul 1 23:03:01 2015

;; MSG SIZE rcvd: 43

From the output message We can tell that localhost has been resolved by DNS server 192.168.0.1, which is the wireless router address. I checked the router setting and the DSN request will be transferred to ISP. So it seems that this problem is not related to any records in my /etc/hosts.

My hosts file is quite simple, there are three effective records:

127.0.0.1 localhost localhost.local

255.255.255.255 broadcasthost

::1 localhost

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Answer 11

Linc Davis

Level 10

209,739 points

Jul 1, 2015 8:34 AM in response to Thomas Qiu

Your DNS is returning an invalid result. If you can't do anything about it, you'll have to change the DNS forwarding setting of your router. You should also revert the change you made to the hosts file, since it serves no purpose.

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