I have been creating A records for subdomains lately, and found that the TTL on the A record matters, but even more important for fast response time is the minimum time to live (reverse cache) on the SOA record. Setting the A record to a TTL of 1 hour and the minimum time to live on the SOA of 1 minute results in almost instant record propagation. Not exactly sure what the SOA minimum time to live even does though.
DNS taking 48+ hours to propagate is a myth
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Re: DNS taking 48+ hours to propagate is a myth
#22Earlier quoted context omitted.
me: web hosting sysadmin also dealing with clients. Yes, people really do freak out about DNS problems, and we quote 72 hours because we have clients on 6 continents. Realistically, it takes 30 minutes - 4 hours for DNS updates to stick. Use http://host-tracker.com/ to check the IP of your site -- that's what we do. It tests something like 80 locations, and the results show the IP returned. You are absolutely correct…
Please provide further detail on these '"big" recursive resolvers' that ignore TTLs. I'm yet to see one in the wild and so I'm somewhat dubious of the claim. (Please don't be vague - post the addresses of the resolvers in question.)
We just moved our DNS from Network Solutions to Route 53 this month, and I can verify that there are indeed resolvers that'll ignore TTLs. Ours were 3-6 hours, but it took some sites about 24 hours to pick up our new SOA.
Which would have been fine - the A records were the same - but no, NetSol instantly starts serving a blank "Business Profile" landing page A-record. Thanks, people who used to run the Internet.
I know one such caching server was ns1.dns.rcn.net. (But only from inside RCN; querying it from Comcast gave different results. Same IP address, so I'm assuming it's anycast.) whatsmydns.net reported others as "Bell South" and "Cox" (I can't recall the locations, I think one was in Georgia).
Re: DNS taking 48+ hours to propagate is a myth
#23This is why I use OpenDNS. You can update THEIR cache. Once I make a change and update their cache, I test again. If all is good, I know the work is done and move on knowing the rest of the world will catch up. http://opendns.com/support/cache
Even if you don't use OpenDNS, it's a great URL to keep bookmarked if you are a site owner. Instantly propagate DNS changes to a few percent of the internet with no worries.
Re: DNS taking 48+ hours to propagate is a myth
#24Earlier quoted context omitted.
This is actually sadly exactly what the author missed in their article. DNS propagation is directly controlled by the TTL setting on a domain entry. TTL stands for Time To Live, this is the number (in seconds) that the DNS entry tells people to keep it active in the DNS server cache's (presuming the DNS server will not over-ride this for either a higher or lower number, which is entirely their choice but not common.)…
me: web hosting sysadmin also dealing with clients. Yes, people really do freak out about DNS problems, and we quote 72 hours because we have clients on 6 continents. Realistically, it takes 30 minutes - 4 hours for DNS updates to stick. Use http://host-tracker.com/ to check the IP of your site -- that's what we do. It tests something like 80 locations, and the results show the IP returned. You are absolutely correct…
Exactly. If you tell someone it's going to take 24 hours and due to caching it takes 48, they're going to be pretty pissed. On the other hand, if you tell someone it's going to take 72 and it really takes 2, they are going to be quite happy.
There are so many variables involved in DNS TTL's, that it really makes more sense to over-estimate things.
Re: DNS taking 48+ hours to propagate is a myth
#25Earlier quoted context omitted.
Please provide further detail on these '"big" recursive resolvers' that ignore TTLs. I'm yet to see one in the wild and so I'm somewhat dubious of the claim. (Please don't be vague - post the addresses of the resolvers in question.)
We just moved our DNS from Network Solutions to Route 53 this month, and I can verify that there are indeed resolvers that'll ignore TTLs. Ours were 3-6 hours, but it took some sites about 24 hours to pick up our new SOA. Which would have been fine - the A records were the same - but no, NetSol instantly starts serving a blank "Business Profile" landing page A-record. Thanks, people who used to run the Internet. I kn…
I just queried ns1.dns.rcn.net for an rrset that has a TTL of 120 seconds and it returned appropriate TTLs.
EDIT: It also does the right thing with even shorter TTLs - try `dig 40.2.+.rp.secret-wg.org txt @ns1.dns.rcn.net`.
Re: DNS taking 48+ hours to propagate is a myth
#26Earlier quoted context omitted.
We just moved our DNS from Network Solutions to Route 53 this month, and I can verify that there are indeed resolvers that'll ignore TTLs. Ours were 3-6 hours, but it took some sites about 24 hours to pick up our new SOA. Which would have been fine - the A records were the same - but no, NetSol instantly starts serving a blank "Business Profile" landing page A-record. Thanks, people who used to run the Internet. I kn…
I just queried ns1.dns.rcn.net for an rrset that has a TTL of 120 seconds and it returned appropriate TTLs. EDIT: It also does the right thing with even shorter TTLs - try `dig 40.2.+.rp.secret-wg.org txt @ns1.dns.rcn.net`.
Oh, it returned appropriate-looking TTLs even at the time; we didn't watch them go down to zero and wrap to their original value, but I suspect that's what they did.
Also, if you're not on RCN, you aren't getting the same NS1 as someone who is. (Again, I assume anycast or load balancing, but I'm handwaving; I haven't understood routing since gated.conf changed.)
My boss was on RCN at home, and I was a few miles away on Comcast. We both pointed dig at 207.172.3.8 and hammered on our domain name; he saw stale results, I saw fresh ones.
Would've loved to have the expertise and tools set up to figure out what went wrong, but we just went to bed and by lunch it sorted itself out.
Re: DNS taking 48+ hours to propagate is a myth
#27Earlier quoted context omitted.
I just queried ns1.dns.rcn.net for an rrset that has a TTL of 120 seconds and it returned appropriate TTLs. EDIT: It also does the right thing with even shorter TTLs - try `dig 40.2.+.rp.secret-wg.org txt @ns1.dns.rcn.net`.
Oh, it returned appropriate-looking TTLs even at the time; we didn't watch them go down to zero and wrap to their original value, but I suspect that's what they did. Also, if you're not on RCN, you aren't getting the same NS1 as someone who is. (Again, I assume anycast or load balancing, but I'm handwaving; I haven't understood routing since gated.conf changed.) My boss was on RCN at home, and I was a few miles away…
I let it cache a record, disabled the zone the record came from and left it to expire. It did. I won't deny that it could behave differently from different addresses, but based on the evidence available I'm sure you can understand why I remain unconvinced.
Re: DNS taking 48+ hours to propagate is a myth
#28Before 2004 Verisign only updated the authoritative DNS twice a day. Then they changed it in January 2004 to every five minutes. So yes, if you are an "old timer" you may remember it really taking up to 48 hours for everywhere around the world to be able to find a new .com But also what they mean by 48 hours is for existing DNS, some users around the world may be on ISPs that heavily cache DNS. Even wifi routers toda…
That's true, but "48 hours to propagate" is misleading because it sounds as though that's business as usual for DNS -- instead of the reality, in which rogue DNS servers cache beyond domains's declared TTL.
Please post the address of one of these rogue DNS servers.