Update A7 instructions (0xcf#417)

labs/a7.md

@@ -143,11 +143,9 @@ now disappeared.
 
 Now, let's unmount the filesystem (try to figure out how) so that we can mount
 a different directory, at `staff2.decal.xcf.sh:/opt/lab7/private/<your username>`
-using `mount` in a similar way to before. What do you
-see in `/mnt/` now? 
+using `mount` in a similar way to before. Tell us if you find the remote path does not exist.
 
-Follow the instructions in the file given
-there. note that you will have to use `sudo` here too to create a new file
+Create something in the mounted directory. Note that you will have to use `sudo` here too to create a new file
 since the directory mounted over NFS is owned by root, not your user.
 
 Again, if NFS takes an excessive time to mount during any of this or you cannot
@@ -179,7 +177,7 @@ more information.
 
 [lab-a6]: /labs/a6#dns-configuration
 
-First, install the `bind9` package on your VM to set up a DNS server.
+First, install the `bind9` package on your VM to set up a DNS server. Uninstall `dnsmasq` if it's previously installed on your VM by `sudo apt purge dnsmasq`.
 
 Let's check the status of the service using `systemctl`. **What command can you run to do this?**