# Can we compare two strings with logstash or elastic search?

**URL:** <https://discuss.elastic.co/t/can-we-compare-two-strings-with-logstash-or-elastic-search/211406>\
**Category:** Logstash\
**Created:** [December 11, 2019, 3:21am UTC](https://discuss.elastic.co/t/can-we-compare-two-strings-with-logstash-or-elastic-search/211406 "2019-12-11T03:21:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Blason](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/blason/32/42284_2.png) [@Blason](https://discuss.elastic.co/u/Blason)\
**Post date:** [December 11, 2019, 3:21am UTC](https://discuss.elastic.co/t/can-we-compare-two-strings-with-logstash-or-elastic-search/211406/1 "2019-12-11T03:21:45Z")

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Hi Folks,

Here is my use case; I have BIND logs being parsed thus extracting queries domain; however I am collecting DNS queries from end users as well using sysmon. So my query is

Since I have BIND server sitting in front of Windows DNS server at present I am not able to see the actual user IP address who has generated the original query.  
Hence wanted to know if I can write a lookup rule like;

if BIND logs [www.google.com](http://www.google.com) AND SYSMON log [www.google.com](http://www.google.com)  
Then add\_field original\_IP?

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [January 8, 2020, 3:21am UTC](https://discuss.elastic.co/t/can-we-compare-two-strings-with-logstash-or-elastic-search/211406/2 "2020-01-08T03:21:59Z")

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