tidying up dns

[browolf]

our dns seems a bit messed up, dunno what effect, if any this is having. Its not like there's any obvious network problems.

 

in the forward lookup zone there's many instances where it looks like a computer has been renamed but the old record hasnt disappeared. for instance

b2-14 and a b2-14xp on 192.168.22.14

 

in the reverse lookup zone especially with dhcp allocated addresses there's sometimes 4 machines on the same ip.

 

ie

nslookup 192.168.105.21

 

------------

Got answer:

HEADER:

opcode = QUERY, id = 1, rcode = NOERROR

header flags: response, auth. answer, want recursion, recursion avail.

questions = 1, answers = 1, authority records = 0, additional = 0

 

QUESTIONS:

11.1.168.192.in-addr.arpa, type = PTR, class = IN

ANSWERS:

-> 11.1.168.192.in-addr.arpa

name = server1.domain.sch.uk

ttl = 1200 (20 mins)

 

------------

Server: server1.domain.sch.uk

Address: 192.168.1.11

 

------------

Got answer:

HEADER:

opcode = QUERY, id = 2, rcode = NOERROR

header flags: response, auth. answer, want recursion, recursion avail.

questions = 1, answers = 4, authority records = 0, additional = 0

 

QUESTIONS:

21.105.168.192.in-addr.arpa, type = PTR, class = IN

ANSWERS:

-> 21.105.168.192.in-addr.arpa

name = t12-02-xp

ttl = 900 (15 mins)

-> 21.105.168.192.in-addr.arpa

name = lsahs-792b6cc71

ttl = 900 (15 mins)

-> 21.105.168.192.in-addr.arpa

name = lap-mac-0907

ttl = 900 (15 mins)

-> 21.105.168.192.in-addr.arpa

name = laptop04je.domain.sch.uk

ttl = 900 (15 mins)

 

------------

Name: t12-02-xp

Address: 192.168.105.21

 

 

we're not abounding with ip conflicts so really the dns has more records than it ought to have. there's 1232 records but we probably only got 750 real ones. (laptops will have 2, wireless & lan)

 

this is the primary dns server. just wondering if I have to go thru it manually. or i can just delete it all and it'll fix itself?

[browolf]

bump.

 

just wanted to know if I can delete all classroom pc dns records and it'll sort itself out or this is a very bad idea and I should do it manually?

[Domino]

Have you tried enabling DNS scavenging?

[stratisphere]

As long as your DHCP server is set todo so, each time a client gets a lease, it'll update DNS.

 

In theory, you can delete all your workstation records (workstation only... dont delete any relating to domain stuff or DC otherwise you'll be screwed!) and when they get new leases, DHCP will re-add them.

 

Occasionally I do the same just to keep it clean.

 

If you want to be sure workstations will re-add the records without suffering downtime from being unable to be resolved, simply restart them.

[Diello]

Using DNS Aging and Scavenging

[SYNACK]

bump.

 

just wanted to know if I can delete all classroom pc dns records and it'll sort itself out or this is a very bad idea and I should do it manually?

 

As long as your system is configured properly you should be able to delete the dns records of hosts and they will reregister the next time they are switched on.

[PiqueABoo]

DNS scavenging is a kludge, in fact it's a horrible kludge. That said it's probaby better than what most people have without it.

 

But spend enought time around wireless laptops that sometimes use wired connections and you'll soon be agreeing with me. The main issue is the order in which DNS returns records when you've got Scavenging's no-refresh interval in action.

 

Doing DHCP + DNS nicely is just very hard.