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Cisco Router ACLs - Add entry

Last Modified: 2012-08-18
I have done done anything with Cisco routers in years, but since the person that normally does this is out, I need to update an ACL on the router.  This is what I have:

An inbound ACL called "ip access-group 101 in" under a GB interface in the config.  There are a bunch of rules in the config in the following format:

access-list 101 permit tcp host host eq domain

What I'd like to do is simply add another rule to the end that blocks anything from  I remember something about having to completely get rid of the ACL then cut and paste from a text file.  But is this necessary if I just want to append to the 101 ACL? Will this work ok (just add to the end of 101):

Router> enable
Router# config t
Router(config)# access-list 101 deny ip any
Router# show access-list 101

I just want to make sure I'm not missing anything.  I don't want to inadvertently take down the whole ACL. I may also need to add a few rules to allow a new system to access dns servers as well:

Router(config)# access-list 101 permit tcp host host eq domain
Router(config)# access-list 101 permit udp host host eq domain

Router is a Cisco 2821 Version 12.1
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