[c-nsp] acces list help and best way to do acess-list

[adrian kok]

Hi

I have this original access-list in running config

access-list 20 deny 192.168.0.0
access-list 20 permit any
line vty 0 4
access-class 20 in



and want to change to add log "access-list 20 deny
192.168.0.0 0.0.0.255 log"

When I change 
router(config)#access-list 20 deny 192.168.0.0
0.0.0.255 log
I realize it can't be changed and have to use "no"
router(config)#no access-list 20 deny 192.168.0.0
0.0.0.255



When I use this command, I almost lost the connection
from anywhere. 

My questions

1/ how can I prevent it happens?

2/ What is the best way to do the access-list in "line
vty"?

3/ ls it good to use log in access-list?
Not sure how router busy or not?

thank you









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