Whats with DNS?

[Spectre]

The real nasty/ugly/horrible thing about dns is many servers are setup to do the caching thing and it can take up to a year for the new updates to fully propagate. Dns is one of those things you avoid touching at all costs.

Absolute BS. The amout of time it will take to propagate your zone is quite simple to calculate. It's the longest TTL for the records [or the TTL in the SOA for older versions that use that as a default and not a minimum]. That is the amount of time that a resolving server can cache the resource records from that zone.

Now you then have to take into account the expire time on the zone. The refresh time is generally how long it's going to take for a slave server to get an update from a primary server [even less now a days with notify and incremental zone transfers]. You -should- be safe with largest TTL + refresh time * depth of slave servers. Depth of slave servers is if you have a slave server using a slave server as master for the zone.

However it -can- take up to TTL+expire time*depth of servers to propogate all changes, since that slave server will be giving out authoritative information until that expire time, even if it hasn't been able to get a zone transfer off the primary.

Genesis mentioned a good point about the serial numbers [almost makes me wonder if he's seen my lecture on DNS]. The -reason- the expire time and depth of servers is important is because you need to understand the sequence space that the serial number arithmetic uses [RFC1982 IIRC] so that you don't exceed the largest meaningful integer when making serial number changes within an expire time. I once had to write up a white paper putting RFC1982 is more reasonable terms because I had a customer that insisted that I was wrong when I told him that yes, regardless what he thinks, 3000120340 was greater than 1. unfortunately I can't seem to find that whitepaper my corporate website anywhere so I can't link you to it.

 

[blacknet]

Hello,

Ahh gotta love it. add a simple bs problem and everyone and their brother becomes a guru on dns. Where else but with scuba can you find this adorable qualities.

Ed

 

[Genesis]

Now now Spectre..... I used to run a rather-large regional ISP and have built two national IP-based networks (one of which was public) in my professional life....

Me thinks I know my way around the DNS system...

BTW, some of the worst offenders when it comes to DNS "islands" (places where the admins have set override TTLs) are on the cache nameservers that large ISPs try to force their customers to use. Fortunately, in most cases you can override this if you (1) know how, and (2) know of a properly-configured caching nameserver to use instead.

 

[Spectre]

add a simple bs problem and everyone and their brother becomes a guru on dns.

Actually; I am.

 

[chrpai]

If you add the line :

69.93.91.170 www.scubaboard.com

to your hosts file, everything will be peachy

In Windows XP it's c:\windows\system32\drivers\etc\hosts - just open in Notepad and add the line. In Windows 98 I believe it's c:\windows\hosts and Win2k should be c:\winnt\system32\drivers\etc\hosts

Jonnythan-

In NT based OS ( NT 3.51,4.0,W2K,XP,2003) its %WINDIR%\system32\drivers\etc\hosts.

In 95 based OS ( 95, 98, 98SE, ME ) its %WINDIR%\hosts.


But we really shouldn't be telling people to do this. Anyone who understands DNS will do it on their own, and the people who don't understand DNS it will just create a problem down the road if scubaboard ever decides to change their IP address.

 

[chrpai]

Actually; I am.

I think you'll find a good number of IT professionals that also happen to scuba. I try to keep my knowledge quiet since so many people around here love to get into pissing contests. I feel very secure in my knowledge and position in the industry so why bother?

 

[Spectre]

But we really shouldn't be telling people to do this. Anyone who understands DNS will do it on their own, and the people who don't understand DNS it will just create a problem down the road if scubaboard ever decides to change their IP address.

Agreed.

You should only use your hosts table for addresses that _you_ have control over and _you_ want to be able to get to regardless of the state of your DNS server. [i.e. like your firewall, or your localhost if you have utilities that use TCP to connect to the localhost].

 

[blacknet]

Actually; I am.

Hello,

Apparently not because you don't have a clue what I said. I thing you took this off topic and this will be the last post i make on this.

Ed

 

[Spectre]

Apparently not because you don't have a clue what I said. I thing you took this off topic and this will be the last post i make on this.

Whatever. I dont think Tech Admin was planning on taking your advise of 'don't touch it' anyway; so I'm not concerned what you think of me.

 

[chrpai]

Well the correct records seem to be propogating..... I've removed my entry from my hosts file.