Examining StackOverflow's existing SOA record values:

primary name server = ns1.p19.dynect.net
serial  = 2009090909
refresh = 3600 (1 hour)
retry   = 600 (10 mins)
expire  = 604800 (7 days)
default TTL = 60 (1 min)

For a site handling ~1M daily pageviews, consider these optimizations:

• Refresh: 7200 (2 hours) - Reduces secondary nameserver load while maintaining reasonable zone sync
• Retry: 300 (5 mins) - Faster retry attempts during failures
• Expire: 1209600 (14 days) - Extended expiration provides more failure resilience
• Default TTL: 300 (5 mins) - Balances DNS cache efficiency with change flexibility

Here's how this would look in a BIND configuration:

@ IN SOA ns1.p19.dynect.net. hostmaster.stackoverflow.com. (
    2023112101 ; serial
    7200       ; refresh (2 hours)
    300        ; retry (5 minutes)
    1209600    ; expire (14 days)
    300        ; minimum TTL (5 minutes)
)

The 1-minute TTL in the current setup means:

• DNS resolvers cache records for only 60 seconds
• High query volume to authoritative servers
• Faster propagation of DNS changes (benefit)

Increasing to 5 minutes reduces server load by ~80% while maintaining reasonable change propagation speed.

For maximum performance with Anycast DNS:

$TTL 300
@ IN SOA ns1.anycast.example.com. hostmaster.example.com. (
    2023112102 ; serial
    10800      ; refresh (3 hours)
    900        ; retry (15 minutes)
    2419200    ; expire (28 days)
    900        ; negative caching TTL
)

After changing SOA values:

1. Monitor DNS query rates
2. Track resolution times
3. Verify zone transfer completion
4. Check for increased cache hit ratios

The SOA (Start of Authority) record is a critical component of DNS configuration, especially for high-traffic websites like Stack Overflow. The current settings shown in the example:

primary name server = ns1.p19.dynect.net
serial  = 2009090909
refresh = 3600 (1 hour)
retry   = 600 (10 mins)
expire  = 604800 (7 days)
default TTL = 60 (1 min)

While these values work, they might not be optimal for a site handling 1M+ daily pageviews.

For websites with significant traffic, consider these adjustments:

refresh = 86400 (24 hours)
retry   = 7200 (2 hours)
expire  = 1209600 (14 days)
default TTL = 300 (5 minutes)

The refresh interval determines how often secondary nameservers check for updates. For stable configurations, 24 hours is reasonable. The retry time should be long enough to handle temporary network issues without creating unnecessary load.

The expire time should be sufficiently long to prevent zone data expiration during extended primary nameserver outages. Two weeks provides a good safety margin.

The default TTL of 60 seconds is too aggressive for most high-traffic sites. A value of 300 seconds (5 minutes) strikes a balance between DNS propagation speed and reducing query load on your nameservers.

Here's how to implement these settings in BIND zone file format:

$ORIGIN example.com.
@ IN SOA ns1.example.com. hostmaster.example.com. (
    2023081501 ; serial
    86400      ; refresh
    7200       ; retry
    1209600    ; expire
    300        ; minimum TTL
)

After implementing changes, monitor DNS query rates and server load. Tools like dig can verify propagation:

dig +nocmd +nocomments +nostats SOA example.com

Remember to increment the serial number (using YYYYMMDDNN format) whenever making changes to your zone file.