dsn move

[Bill Pontius]

We have 2 hp unix boxes (a 715 and a G40) handling the dns. The 715 support life has now ended and would like to move this dsn to another box but have the following questions.
1. How much space is required for dns.
2. How do I tell what users are using what server and how would I change the obsolete ones.
3. How you we tell which server DHCP is giving out and what is the best way to change it if it gives out the obsolete one - force renewal or wait to expire ip address.
4. How to determine all that are still looking at obsolete one and change them.
5. Can I get a count or % of people using the 2 dns boxes.

[Jordan Bean]

Are the two in a master/slave configuration? Which one is the master? The upgrade path is more difficult if the master is being replaced. Which version of BIND is running on each? You may concider upgrading to BIND 8.2.4 or 9.1.3. If you do this right, you won't have to reconfigure the DHCP server or clients and name resolution won't be interupted.

[Jim Turner]

Hi Bill,

1. Space for DNS?
Since BIND is included with HP-UX, the space required is entirely dependent upon the size of your zone files. My zone files are in /etc/named.dat. I determined the size to be 509KB thus:
# du -kxs /etc/named.dat
509 /etc/named.dat

2. Handling users of the obsolete server?
Two options here -- both making the switch a non-issue. First, you could let your new DNS server assume the name and IP of the obsolete box. Secondly, you could simply update your DHCP server and force everyone to release/renew before downing the obsolete DNS server. You don't mention whether or not your clients are Winblows, HP-UX, or both. If HP-UX, both servers should be in /etc/resolv.conf making the downing of one a very small impact.

3. Which server DHCP is giving out ... best way to change it?
For the first part, I'd recommend looking at the config of your DHCP server. See answer to #2 for second part.

4. Determine all that are still looking at obsolete one and change them?
See #2

5. Can I get a count or % of people using the 2 dns boxes?
Use the -d debug option when starting named on the DNS server, and you can get enough usage information to choke a horse.
man 1m named

If you have to do *anything* with DNS, O'Reilly's "DNS and BIND" is required reading.
http://www.oreilly.com/catalog/dns4/

Cheers,
Jim

[Bill Thorsteinson]

1. Disk space has been covered above. Memory usage
can be high depending on the variety of requests
the server responds to. Check the memory size of
the server after it has been running a week or two.
CPU and network traffic are generally quite low.

Depending on your load an old 486 running Linux
could be sufficent. Make sure it has enough memory.

2. You need to check all your DHCP configurations and
all non-DHCP systems as in answer 3 or check the log
generated using answer 4.

Alternatively you can transfer the IP and BIND services
to another system. You could add the IP as an alias on an existing system. If you can avoid it don't add the IP as an alias to an existing name
server. Lookups by name will follow the IP.

3. Other than checking the configuration files of the
DHCP server. You can check winipcfg on a Windows
9x pc using DHCP. It will show the DNS server if you
press the More Info button. Press the ... button to see
the list. As long as the server isn't the only DNS server
you can remove it, although it will slow down resolution.
On unix check /etc/resolve.conf of a server using DHCP
to get its address. Systems not using DHCP are hard
coded.

4. You can log all queries by adding
channel query)log {
file "query.log" versions 3 size 20m;
};
and
logging {
category queries { query_log };
};
to the named.conf file. Add the category entry into
an existing logging entry if you have it. Then reload
your bind server.

5. You users should all be using both DNS server in a
round robin fashion. Usage should be 50/50 for
two servers. Check the bind logging documentation
and enable statistics.