I have a apache server running on CentOS 6.5 server. In log files 25% of records are like this

```
000.000.000.000 - - [24/Jul/2014:04:15:10 +0000] "GET /address/of/the/page.html HTTP/1.1" 200 20341 "-" "Mozilla/4.0 

```

But rest of 75% of logs are like this, without IP

```
- - [24/Jul/2014:04:15:10 +0000] "GET /address/of/the/page.html HTTP/1.1" 200 20341 "-" "Mozilla/4.0

```

Can somebody tell me what is the problem?
Thanks!