Bind

cd /etc/bind vi db.nas-admin.org


 * 3 gets you to the most important line in the whole file

the serial #

every time you make an edit in a db file for bind you MUST update that line or the changes will not be picked up

remember the. at the end

the AXFR is the "zone transfer" to our servers that front for us.

Jan 28 08:30:17 fran named[24445]: zone transfer (AXFR) of "nas-admin.org" (IN) to [140.211.166.126].54082 serial 2011012701

so...basically remember 3 things

1) always update the serial

2) cnames are "aliases" for other machines

3) always end the names in the right hand side with a . or else you will get something like this IP Addresses do not need a . at the end.

IF you forget you will get something like this: foo.nas-admin.org.nas-admin.org

if you really wanted foo.nas-admin.org there are 2 wasys to do it

1) just simply foo and it will automagically append .nas-admin.org

2) foo.nas-admin.org.

Then:

service bind restart (or reload)

followed by: tail -f /var/log/daemon.log

DNS is a big TREE.

the top levels (called TLD's) or Top Level Domains are housed in those servers (like 8-9 of them)

they basically point to things like .org and .tw etc

and .org is someplace else.

and .org knows how to get to novaports

and novaports (us) knows how to get to pulsar

 got it

so in this case the question gets asked 4X

 hence... pulsar.novaports.org

correct

there are like 5 different main kinds of records

NS or "nameservers"...these are the nameservers that give the answer to others...

in our case we are using the nameservers @ osuosl.

see them?

 yup

okay below that are MX

mx means "mail exchanger"

we have 1

fran

 whats gabe?

if we had several they would all be listed

OLD long dead server...so this is cruft

now if we had several the numbers like the 10 mean something

a number of 10 would be prefered over a 20 server

below that are the A records

or Address records

those point to "our" machines

below that are the CNAMES or "common names"

those are like www and other things...

so blog and mentoring point to fiona

but www points to fran

there are a couple of special symbols...

one is @

that means just the domain name...aka nas-admin.rog

er org.

IP addresses do not need a. at the end

you see ns1 and ns2 there?

 yup

see anything different?

 @ is pointing them to nas-admin.org

 @ is pointing them to .nas-admin.org

so when someone asks for who knows about nas-admin.org the 2 servers that do are ns1 and ns2

but there is something else different about them.

 not an A record?

no. at the end

therefore what happens....

 .nas-admin.org

yes, correct..it appends .nas-admin.org

there are a few more types...but only 1 is in common use

and thats a PTR

lets close this

okay this is called an: in-addr.arpa file

it contains a list of IP addresses and the names associated with that address

its also known as the "reverse" lookup table.

the "dotted quads" are written in reverse order here

so the real ip addresses are: 140.211.169.x

but the name is the reverse of that

130-190.168.211.140-in-addr.arpa

when someone says "whats this stupid server @ 140.211.169.165" and asks DNS for its "name" this file is consulted

and its melo.openembedded.rog

.org

this is especially important for mail servers.